Attachment 348928 Details for Bug 189303 – Patch

[patch] Patch

bug-189303-20180905175734.patch (text/plain), 758.01 KB, created by Ms2ger (he/him; ⌚ UTC+1/+2) on 2018-09-05 08:57:37 PDT

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Filename:

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Creator: Ms2ger (he/him; ⌚ UTC+1/+2)

Created: 2018-09-05 08:57:37 PDT

Size: 758.01 KB

patch

obsolete

>Subversion Revision: 235664
>diff --git a/LayoutTests/imported/w3c/ChangeLog b/LayoutTests/imported/w3c/ChangeLog
>index cf7b31b0ff0b0823f5dc2948d8d5e026eb1b9ac9..810f2a5728cd634148e06f1509d0643a84c28f6a 100644
>--- a/LayoutTests/imported/w3c/ChangeLog
>+++ b/LayoutTests/imported/w3c/ChangeLog
>@@ -1,3 +1,193 @@
>+2018-09-05  Ms2ger  <Ms2ger@igalia.com>
>+
>+        Update idlharness.js and webidl2.js.
>+        https://bugs.webkit.org/show_bug.cgi?id=189303
>+
>+        Reviewed by Youenn Fablet.
>+
>+        * web-platform-tests/dom/interfaces.html: Updated for harness changes.
>+        * web-platform-tests/hr-time/idlharness.html: Updated for harness changes.
>+        * web-platform-tests/interfaces/IndexedDB.idl: Updated for harness changes.
>+        * web-platform-tests/interfaces/intersection-observer.idl: Added.
>+        * web-platform-tests/resources/idlharness.js:
>+        * web-platform-tests/resources/webidl2/CHANGELOG.md: Added.
>+        * web-platform-tests/resources/webidl2/README.md:
>+        * web-platform-tests/resources/webidl2/checker/index.html: Added.
>+        * web-platform-tests/resources/webidl2/checker/w3c-import.log: Added.
>+        * web-platform-tests/resources/webidl2/lib/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/lib/webidl2.js:
>+        * web-platform-tests/resources/webidl2/lib/writer.js:
>+        * web-platform-tests/resources/webidl2/package-lock.json: Added.
>+        * web-platform-tests/resources/webidl2/package.json:
>+        * web-platform-tests/resources/webidl2/test/invalid.js:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/array.widl: Renamed from LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/array.widl.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/caller.widl: Renamed from LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/caller.widl.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/duplicate.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/enum-empty.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/enum-wo-comma.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/exception.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/extattr-empty-ids.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/id-underscored-number.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/implements_and_includes_ws.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/iterator.widl: Renamed from LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterator.widl.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/namespace-readwrite.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon-callback.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/promise-nullable.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/promise-with-extended-attribute.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/record-key-with-extended-attribute.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/record-single.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/setter-creator.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/spaced-negative-infinity.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/spaced-variadic.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/stray-slash.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.widl: Renamed from LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.idl.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl:
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/union-dangling-or.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/union-one.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/union-zero.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/unknown-generic.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/idl/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/array.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/caller.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/duplicate.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/enum-empty.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/enum-wo-comma.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/enum.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/exception.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/extattr-empty-ids.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/id-underscored-number.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/implements_and_includes_ws.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/iterator.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/module.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/namespace-readwrite.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon-callback.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/promise-nullable.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/promise-with-extended-attribute.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/raises.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/record-key-with-extended-attribute.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/record-key.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/record-single.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/setter-creator.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/spaced-negative-infinity.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/spaced-variadic.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/stray-slash.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json:
>+        * web-platform-tests/resources/webidl2/test/invalid/json/union-dangling-or.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/union-one.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/union-zero.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/unknown-generic.json: Added.
>+        * web-platform-tests/resources/webidl2/test/invalid/json/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/syntax.js:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/exception-inheritance.widl: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/exception.widl: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/identifier-qualified-names.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/indexed-properties.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/mixin.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/overloading.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/promise-void.widl: Added.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/record.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/serializer.widl: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.widl: Renamed from LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.idl.
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl:
>+        * web-platform-tests/resources/webidl2/test/syntax/idl/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/allowany.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/array.json: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/attributes.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/callback.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/caller.json: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/constants.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/constructor.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/dictionary.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/documentation-dos.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/documentation.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/enum.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/exception.json: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/generic.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/identifier-qualified-names.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/implements.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/indexed-properties.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/inherits-getter.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/interface-inherits.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/iterable.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/iterator.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/maplike.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/mixin.json: Added.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/namespace.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/nullable.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/nullableobjects.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/operation-optional-arg.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/overloading.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/primitives.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/promise-void.json: Added.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/record.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/sequence.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/serializer.json: Removed.
>+        * web-platform-tests/resources/webidl2/test/syntax/json/setlike.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/static.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/stringifier-custom.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/stringifier.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/treatasnull.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/treatasundefined.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/typedef-union.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/typedef.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/typesuffixes.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/uniontype.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/variadic-operations.json:
>+        * web-platform-tests/resources/webidl2/test/syntax/json/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/util/acquire.js: Added.
>+        * web-platform-tests/resources/webidl2/test/util/collect.js: Added.
>+        * web-platform-tests/resources/webidl2/test/util/w3c-import.log: Added.
>+        * web-platform-tests/resources/webidl2/test/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/web/w3c-import.log:
>+        * web-platform-tests/resources/webidl2/test/writer.js: Added.
>+        * web-platform-tests/resources/webidl2/w3c-import.log:
>+
> 2018-09-04  Frederic Wang  <fwang@igalia.com>
> 
>         Add basic support for ScrollIntoViewOptions
>diff --git a/LayoutTests/http/wpt/entries-api/interfaces-expected.txt b/LayoutTests/http/wpt/entries-api/interfaces-expected.txt
>index afec09c2a5b3227ac2dd43b3c0168749eed0e521..c69bc63b4896477948bd77563d8bc96a3b0e2a55 100644
>--- a/LayoutTests/http/wpt/entries-api/interfaces-expected.txt
>+++ b/LayoutTests/http/wpt/entries-api/interfaces-expected.txt
>@@ -1,12 +1,14 @@
> Entries API IDL tests
> 
> 
>+PASS Partial interface File: original interface defined 
>+PASS Partial interface HTMLInputElement: original interface defined 
>+PASS Partial interface DataTransferItem: original interface defined 
> PASS ErrorCallback interface: existence and properties of interface object 
> PASS ErrorCallback interface: existence and properties of interface prototype object 
> PASS ErrorCallback interface: existence and properties of interface prototype object's "constructor" property 
> PASS ErrorCallback interface: existence and properties of interface prototype object's @@unscopables property 
> PASS ErrorCallback interface: operation handleEvent(DOMException) 
>-PASS Unscopable handled correctly for handleEvent(DOMException) on ErrorCallback 
> PASS FileSystemEntry interface: existence and properties of interface object 
> PASS FileSystemEntry interface object length 
> PASS FileSystemEntry interface object name 
>@@ -14,17 +16,11 @@ PASS FileSystemEntry interface: existence and properties of interface prototype
> PASS FileSystemEntry interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemEntry interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemEntry interface: attribute isFile 
>-PASS Unscopable handled correctly for isFile property on FileSystemEntry 
> PASS FileSystemEntry interface: attribute isDirectory 
>-PASS Unscopable handled correctly for isDirectory property on FileSystemEntry 
> PASS FileSystemEntry interface: attribute name 
>-PASS Unscopable handled correctly for name property on FileSystemEntry 
> PASS FileSystemEntry interface: attribute fullPath 
>-PASS Unscopable handled correctly for fullPath property on FileSystemEntry 
> PASS FileSystemEntry interface: attribute filesystem 
>-PASS Unscopable handled correctly for filesystem property on FileSystemEntry 
> PASS FileSystemEntry interface: operation getParent(FileSystemEntryCallback, ErrorCallback) 
>-PASS Unscopable handled correctly for getParent(FileSystemEntryCallback, ErrorCallback) on FileSystemEntry 
> PASS FileSystemDirectoryEntry interface: existence and properties of interface object 
> PASS FileSystemDirectoryEntry interface object length 
> PASS FileSystemDirectoryEntry interface object name 
>@@ -32,17 +28,13 @@ PASS FileSystemDirectoryEntry interface: existence and properties of interface p
> PASS FileSystemDirectoryEntry interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemDirectoryEntry interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemDirectoryEntry interface: operation createReader() 
>-PASS Unscopable handled correctly for createReader() on FileSystemDirectoryEntry 
> PASS FileSystemDirectoryEntry interface: operation getFile(USVString, FileSystemFlags, FileSystemEntryCallback, ErrorCallback) 
>-PASS Unscopable handled correctly for getFile(USVString, FileSystemFlags, FileSystemEntryCallback, ErrorCallback) on FileSystemDirectoryEntry 
> PASS FileSystemDirectoryEntry interface: operation getDirectory(USVString, FileSystemFlags, FileSystemEntryCallback, ErrorCallback) 
>-PASS Unscopable handled correctly for getDirectory(USVString, FileSystemFlags, FileSystemEntryCallback, ErrorCallback) on FileSystemDirectoryEntry 
> PASS FileSystemEntryCallback interface: existence and properties of interface object 
> PASS FileSystemEntryCallback interface: existence and properties of interface prototype object 
> PASS FileSystemEntryCallback interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemEntryCallback interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemEntryCallback interface: operation handleEvent(FileSystemEntry) 
>-PASS Unscopable handled correctly for handleEvent(FileSystemEntry) on FileSystemEntryCallback 
> PASS FileSystemDirectoryReader interface: existence and properties of interface object 
> PASS FileSystemDirectoryReader interface object length 
> PASS FileSystemDirectoryReader interface object name 
>@@ -50,13 +42,11 @@ PASS FileSystemDirectoryReader interface: existence and properties of interface
> PASS FileSystemDirectoryReader interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemDirectoryReader interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemDirectoryReader interface: operation readEntries(FileSystemEntriesCallback, ErrorCallback) 
>-PASS Unscopable handled correctly for readEntries(FileSystemEntriesCallback, ErrorCallback) on FileSystemDirectoryReader 
> PASS FileSystemEntriesCallback interface: existence and properties of interface object 
> PASS FileSystemEntriesCallback interface: existence and properties of interface prototype object 
> PASS FileSystemEntriesCallback interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemEntriesCallback interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemEntriesCallback interface: operation handleEvent([object Object]) 
>-PASS Unscopable handled correctly for handleEvent([object Object]) on FileSystemEntriesCallback 
> PASS FileSystemFileEntry interface: existence and properties of interface object 
> PASS FileSystemFileEntry interface object length 
> PASS FileSystemFileEntry interface object name 
>@@ -64,13 +54,11 @@ PASS FileSystemFileEntry interface: existence and properties of interface protot
> PASS FileSystemFileEntry interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystemFileEntry interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystemFileEntry interface: operation file(FileCallback, ErrorCallback) 
>-PASS Unscopable handled correctly for file(FileCallback, ErrorCallback) on FileSystemFileEntry 
> PASS FileCallback interface: existence and properties of interface object 
> PASS FileCallback interface: existence and properties of interface prototype object 
> PASS FileCallback interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileCallback interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileCallback interface: operation handleEvent(File) 
>-PASS Unscopable handled correctly for handleEvent(File) on FileCallback 
> PASS FileSystem interface: existence and properties of interface object 
> PASS FileSystem interface object length 
> PASS FileSystem interface object name 
>@@ -78,18 +66,12 @@ PASS FileSystem interface: existence and properties of interface prototype objec
> PASS FileSystem interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileSystem interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileSystem interface: attribute name 
>-PASS Unscopable handled correctly for name property on FileSystem 
> PASS FileSystem interface: attribute root 
>-PASS Unscopable handled correctly for root property on FileSystem 
> PASS File interface: attribute webkitRelativePath 
>-PASS Unscopable handled correctly for webkitRelativePath property on File 
> PASS File interface: new File(["myFileBits"], "myFileName") must inherit property "webkitRelativePath" with the proper type 
> PASS HTMLInputElement interface: attribute webkitdirectory 
>-PASS Unscopable handled correctly for webkitdirectory property on HTMLInputElement 
> PASS HTMLInputElement interface: attribute webkitEntries 
>-PASS Unscopable handled correctly for webkitEntries property on HTMLInputElement 
> PASS HTMLInputElement interface: file_input must inherit property "webkitdirectory" with the proper type 
> PASS HTMLInputElement interface: file_input must inherit property "webkitEntries" with the proper type 
> PASS DataTransferItem interface: operation webkitGetAsEntry() 
>-PASS Unscopable handled correctly for webkitGetAsEntry() on DataTransferItem 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness-expected.txt
>index 0add2773e44804a84486ed6235adb9895b37462b..ee867870cf9185c806f5f0ee3b3506c69084bce8 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness-expected.txt
>@@ -1,11 +1,9 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> File API automated IDL tests
> 
> 
> PASS URL interface: operation createObjectURL(Blob) 
>-PASS Unscopable handled correctly for createObjectURL(Blob) on URL 
> PASS URL interface: operation revokeObjectURL(DOMString) 
>-PASS Unscopable handled correctly for revokeObjectURL(DOMString) on URL 
> PASS Blob interface: existence and properties of interface object 
> PASS Blob interface object length 
> PASS Blob interface object name 
>@@ -13,11 +11,8 @@ PASS Blob interface: existence and properties of interface prototype object
> PASS Blob interface: existence and properties of interface prototype object's "constructor" property 
> PASS Blob interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Blob interface: attribute size 
>-PASS Unscopable handled correctly for size property on Blob 
> PASS Blob interface: attribute type 
>-PASS Unscopable handled correctly for type property on Blob 
> PASS Blob interface: operation slice(long long, long long, DOMString) 
>-PASS Unscopable handled correctly for slice(long long, long long, DOMString) on Blob 
> PASS Blob must be primary interface of new Blob(["TEST"]) 
> PASS Stringification of new Blob(["TEST"]) 
> PASS Blob interface: new Blob(["TEST"]) must inherit property "size" with the proper type 
>@@ -31,9 +26,7 @@ PASS File interface: existence and properties of interface prototype object
> PASS File interface: existence and properties of interface prototype object's "constructor" property 
> PASS File interface: existence and properties of interface prototype object's @@unscopables property 
> PASS File interface: attribute name 
>-PASS Unscopable handled correctly for name property on File 
> PASS File interface: attribute lastModified 
>-PASS Unscopable handled correctly for lastModified property on File 
> PASS File must be primary interface of new File(["myFileBits"], "myFileName") 
> PASS Stringification of new File(["myFileBits"], "myFileName") 
> PASS File interface: new File(["myFileBits"], "myFileName") must inherit property "name" with the proper type 
>@@ -49,9 +42,7 @@ PASS FileList interface: existence and properties of interface prototype object
> PASS FileList interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileList interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileList interface: operation item(unsigned long) 
>-PASS Unscopable handled correctly for item(unsigned long) on FileList 
> PASS FileList interface: attribute length 
>-PASS Unscopable handled correctly for length property on FileList 
> PASS FileList must be primary interface of file_input.files 
> PASS Stringification of file_input.files 
> PASS FileList interface: file_input.files must inherit property "item(unsigned long)" with the proper type 
>@@ -64,15 +55,10 @@ PASS FileReader interface: existence and properties of interface prototype objec
> PASS FileReader interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileReader interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileReader interface: operation readAsArrayBuffer(Blob) 
>-PASS Unscopable handled correctly for readAsArrayBuffer(Blob) on FileReader 
> PASS FileReader interface: operation readAsBinaryString(Blob) 
>-PASS Unscopable handled correctly for readAsBinaryString(Blob) on FileReader 
> PASS FileReader interface: operation readAsText(Blob, DOMString) 
>-PASS Unscopable handled correctly for readAsText(Blob, DOMString) on FileReader 
> PASS FileReader interface: operation readAsDataURL(Blob) 
>-PASS Unscopable handled correctly for readAsDataURL(Blob) on FileReader 
> PASS FileReader interface: operation abort() 
>-PASS Unscopable handled correctly for abort() on FileReader 
> PASS FileReader interface: constant EMPTY on interface object 
> PASS FileReader interface: constant EMPTY on interface prototype object 
> PASS FileReader interface: constant LOADING on interface object 
>@@ -80,23 +66,14 @@ PASS FileReader interface: constant LOADING on interface prototype object
> PASS FileReader interface: constant DONE on interface object 
> PASS FileReader interface: constant DONE on interface prototype object 
> PASS FileReader interface: attribute readyState 
>-PASS Unscopable handled correctly for readyState property on FileReader 
> PASS FileReader interface: attribute result 
>-PASS Unscopable handled correctly for result property on FileReader 
> PASS FileReader interface: attribute error 
>-PASS Unscopable handled correctly for error property on FileReader 
> PASS FileReader interface: attribute onloadstart 
>-PASS Unscopable handled correctly for onloadstart property on FileReader 
> PASS FileReader interface: attribute onprogress 
>-PASS Unscopable handled correctly for onprogress property on FileReader 
> PASS FileReader interface: attribute onload 
>-PASS Unscopable handled correctly for onload property on FileReader 
> PASS FileReader interface: attribute onabort 
>-PASS Unscopable handled correctly for onabort property on FileReader 
> PASS FileReader interface: attribute onerror 
>-PASS Unscopable handled correctly for onerror property on FileReader 
> PASS FileReader interface: attribute onloadend 
>-PASS Unscopable handled correctly for onloadend property on FileReader 
> PASS FileReader must be primary interface of new FileReader() 
> PASS Stringification of new FileReader() 
> PASS FileReader interface: new FileReader() must inherit property "readAsArrayBuffer(Blob)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.html b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.html
>index 0cd604cccc302a1768bb6232ef218349e7755907..db6592e6220d02b608f504f8f2a654779c8b0241 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.html
>@@ -20,37 +20,23 @@
>     </form>
> 
>     <script>
>-var file_input;
>-setup(function() {
>-    var idl_array = new IdlArray();
>-
>-    var request = new XMLHttpRequest();
>-    request.open("GET", "/interfaces/FileAPI.idl");
>-    request.send();
>-    request.onload = function() {
>-        var idls = request.responseText;
>-
>-        idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface ArrayBuffer {};");
>-        idl_array.add_untested_idls("interface URL {};");
>-        idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface EventTarget {};");
>-        idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface Event {};");
>-        idl_array.add_untested_idls("[TreatNonCallableAsNull] callback EventHandlerNonNull = any (Event event);");
>-        idl_array.add_untested_idls("typedef EventHandlerNonNull? EventHandler;");
>-
>-        idl_array.add_idls(idls);
>-
>-        file_input = document.querySelector("#fileChooser");
>-        idl_array.add_objects({
>+      'use strict';
>+
>+      idl_test(
>+        ['FileAPI'],
>+        ['dom', 'html', 'url'],
>+        idl_array => {
>+          idl_array.add_untested_idls(
>+            "[Exposed=(Window,Worker)] interface ArrayBuffer {};"
>+          );
>+          idl_array.add_objects({
>             Blob: ['new Blob(["TEST"])'],
>             File: ['new File(["myFileBits"], "myFileName")'],
>-            FileList: ['file_input.files'],
>+            FileList: ['document.querySelector("#fileChooser").files'],
>             FileReader: ['new FileReader()']
>-        });
>-
>-        idl_array.test();
>-        done();
>-  };
>-}, {explicit_done: true});
>+          });
>+        }
>+      );
>     </script>
> 
>   </body>
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker-expected.txt
>index 646aa5542691272ffc23314f6661089d8aeabca9..13ff323fb8dc08625682859411c60a0375a882ce 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker-expected.txt
>@@ -11,11 +11,8 @@ PASS Blob interface: existence and properties of interface prototype object
> PASS Blob interface: existence and properties of interface prototype object's "constructor" property 
> PASS Blob interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Blob interface: attribute size 
>-PASS Unscopable handled correctly for size property on Blob 
> PASS Blob interface: attribute type 
>-PASS Unscopable handled correctly for type property on Blob 
> PASS Blob interface: operation slice(long long, long long, DOMString) 
>-PASS Unscopable handled correctly for slice(long long, long long, DOMString) on Blob 
> PASS Blob must be primary interface of new Blob(["TEST"]) 
> PASS Stringification of new Blob(["TEST"]) 
> PASS Blob interface: new Blob(["TEST"]) must inherit property "size" with the proper type 
>@@ -29,9 +26,7 @@ FAIL File interface: existence and properties of interface prototype object asse
> FAIL File interface: existence and properties of interface prototype object's "constructor" property assert_own_property: self does not have own property "File" expected property "File" missing
> FAIL File interface: existence and properties of interface prototype object's @@unscopables property assert_own_property: self does not have own property "File" expected property "File" missing
> FAIL File interface: attribute name assert_own_property: self does not have own property "File" expected property "File" missing
>-PASS Unscopable handled correctly for name property on File 
> FAIL File interface: attribute lastModified assert_own_property: self does not have own property "File" expected property "File" missing
>-PASS Unscopable handled correctly for lastModified property on File 
> FAIL File must be primary interface of new File(["myFileBits"], "myFileName") assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: File"
> FAIL Stringification of new File(["myFileBits"], "myFileName") assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: File"
> FAIL File interface: new File(["myFileBits"], "myFileName") must inherit property "name" with the proper type assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: File"
>@@ -47,9 +42,7 @@ FAIL FileList interface: existence and properties of interface prototype object
> FAIL FileList interface: existence and properties of interface prototype object's "constructor" property assert_own_property: self does not have own property "FileList" expected property "FileList" missing
> FAIL FileList interface: existence and properties of interface prototype object's @@unscopables property assert_own_property: self does not have own property "FileList" expected property "FileList" missing
> FAIL FileList interface: operation item(unsigned long) assert_own_property: self does not have own property "FileList" expected property "FileList" missing
>-PASS Unscopable handled correctly for item(unsigned long) on FileList 
> FAIL FileList interface: attribute length assert_own_property: self does not have own property "FileList" expected property "FileList" missing
>-PASS Unscopable handled correctly for length property on FileList 
> PASS FileReader interface: existence and properties of interface object 
> PASS FileReader interface object length 
> PASS FileReader interface object name 
>@@ -57,15 +50,10 @@ PASS FileReader interface: existence and properties of interface prototype objec
> PASS FileReader interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileReader interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileReader interface: operation readAsArrayBuffer(Blob) 
>-PASS Unscopable handled correctly for readAsArrayBuffer(Blob) on FileReader 
> PASS FileReader interface: operation readAsBinaryString(Blob) 
>-PASS Unscopable handled correctly for readAsBinaryString(Blob) on FileReader 
> PASS FileReader interface: operation readAsText(Blob, DOMString) 
>-PASS Unscopable handled correctly for readAsText(Blob, DOMString) on FileReader 
> PASS FileReader interface: operation readAsDataURL(Blob) 
>-PASS Unscopable handled correctly for readAsDataURL(Blob) on FileReader 
> PASS FileReader interface: operation abort() 
>-PASS Unscopable handled correctly for abort() on FileReader 
> PASS FileReader interface: constant EMPTY on interface object 
> PASS FileReader interface: constant EMPTY on interface prototype object 
> PASS FileReader interface: constant LOADING on interface object 
>@@ -73,23 +61,14 @@ PASS FileReader interface: constant LOADING on interface prototype object
> PASS FileReader interface: constant DONE on interface object 
> PASS FileReader interface: constant DONE on interface prototype object 
> PASS FileReader interface: attribute readyState 
>-PASS Unscopable handled correctly for readyState property on FileReader 
> PASS FileReader interface: attribute result 
>-PASS Unscopable handled correctly for result property on FileReader 
> PASS FileReader interface: attribute error 
>-PASS Unscopable handled correctly for error property on FileReader 
> PASS FileReader interface: attribute onloadstart 
>-PASS Unscopable handled correctly for onloadstart property on FileReader 
> PASS FileReader interface: attribute onprogress 
>-PASS Unscopable handled correctly for onprogress property on FileReader 
> PASS FileReader interface: attribute onload 
>-PASS Unscopable handled correctly for onload property on FileReader 
> PASS FileReader interface: attribute onabort 
>-PASS Unscopable handled correctly for onabort property on FileReader 
> PASS FileReader interface: attribute onerror 
>-PASS Unscopable handled correctly for onerror property on FileReader 
> PASS FileReader interface: attribute onloadend 
>-PASS Unscopable handled correctly for onloadend property on FileReader 
> PASS FileReader must be primary interface of new FileReader() 
> PASS Stringification of new FileReader() 
> PASS FileReader interface: new FileReader() must inherit property "readAsArrayBuffer(Blob)" with the proper type 
>@@ -120,13 +99,9 @@ PASS FileReaderSync interface: existence and properties of interface prototype o
> PASS FileReaderSync interface: existence and properties of interface prototype object's "constructor" property 
> PASS FileReaderSync interface: existence and properties of interface prototype object's @@unscopables property 
> PASS FileReaderSync interface: operation readAsArrayBuffer(Blob) 
>-PASS Unscopable handled correctly for readAsArrayBuffer(Blob) on FileReaderSync 
> PASS FileReaderSync interface: operation readAsBinaryString(Blob) 
>-PASS Unscopable handled correctly for readAsBinaryString(Blob) on FileReaderSync 
> PASS FileReaderSync interface: operation readAsText(Blob, DOMString) 
>-PASS Unscopable handled correctly for readAsText(Blob, DOMString) on FileReaderSync 
> PASS FileReaderSync interface: operation readAsDataURL(Blob) 
>-PASS Unscopable handled correctly for readAsDataURL(Blob) on FileReaderSync 
> PASS FileReaderSync must be primary interface of new FileReaderSync() 
> PASS Stringification of new FileReaderSync() 
> PASS FileReaderSync interface: new FileReaderSync() must inherit property "readAsArrayBuffer(Blob)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker.js b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker.js
>index fdf208df7c431446eedc9b50dfd9647cf0b9836f..5bf82e0b890327d0f389b5cbe95b39eacadb42dd 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/FileAPI/idlharness.worker.js
>@@ -1,31 +1,21 @@
> importScripts("/resources/testharness.js");
> importScripts("/resources/WebIDLParser.js", "/resources/idlharness.js");
> 
>-var request = new XMLHttpRequest();
>-request.open("GET", "/interfaces/FileAPI.idl");
>-request.send();
>-request.onload = function() {
>-    var idl_array = new IdlArray();
>-    var idls = request.responseText;
>+'use strict';
> 
>-    idl_array.add_untested_idls("[Global] interface Window { };");
>+// https://w3c.github.io/FileAPI/
> 
>+idl_test(
>+  ['FileAPI'],
>+  ['dom', 'html', 'url'],
>+  idl_array => {
>     idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface ArrayBuffer {};");
>-    idl_array.add_untested_idls("interface URL {};");
>-    idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface EventTarget {};");
>-    idl_array.add_untested_idls("[Exposed=(Window,Worker)] interface Event {};");
>-    idl_array.add_untested_idls("[TreatNonCallableAsNull] callback EventHandlerNonNull = any (Event event);");
>-    idl_array.add_untested_idls("typedef EventHandlerNonNull? EventHandler;");
>-
>-    idl_array.add_idls(idls);
>-
>     idl_array.add_objects({
>-        Blob: ['new Blob(["TEST"])'],
>-        File: ['new File(["myFileBits"], "myFileName")'],
>-        FileReader: ['new FileReader()'],
>-        FileReaderSync: ['new FileReaderSync()']
>+      Blob: ['new Blob(["TEST"])'],
>+      File: ['new File(["myFileBits"], "myFileName")'],
>+      FileReader: ['new FileReader()'],
>+      FileReaderSync: ['new FileReaderSync()']
>     });
>-
>-    idl_array.test();
>-    done();
>-};
>+  }
>+);
>+done();
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https-expected.txt
>index 84bf5c4c2eceec11e6d1dfd3d8e2115933f0a270..21346124430928d4f0af58ef26d0c30b3e5d8f70 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https-expected.txt
>@@ -10,9 +10,7 @@ PASS Crypto interface: existence and properties of interface prototype object
> PASS Crypto interface: existence and properties of interface prototype object's "constructor" property 
> PASS Crypto interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Crypto interface: attribute subtle 
>-PASS Unscopable handled correctly for subtle property on Crypto 
> PASS Crypto interface: operation getRandomValues(ArrayBufferView) 
>-PASS Unscopable handled correctly for getRandomValues(ArrayBufferView) on Crypto 
> PASS Crypto must be primary interface of crypto 
> PASS Stringification of crypto 
> PASS Crypto interface: crypto must inherit property "subtle" with the proper type 
>@@ -25,13 +23,9 @@ PASS CryptoKey interface: existence and properties of interface prototype object
> PASS CryptoKey interface: existence and properties of interface prototype object's "constructor" property 
> PASS CryptoKey interface: existence and properties of interface prototype object's @@unscopables property 
> PASS CryptoKey interface: attribute type 
>-PASS Unscopable handled correctly for type property on CryptoKey 
> PASS CryptoKey interface: attribute extractable 
>-PASS Unscopable handled correctly for extractable property on CryptoKey 
> PASS CryptoKey interface: attribute algorithm 
>-PASS Unscopable handled correctly for algorithm property on CryptoKey 
> PASS CryptoKey interface: attribute usages 
>-PASS Unscopable handled correctly for usages property on CryptoKey 
> PASS SubtleCrypto interface: existence and properties of interface object 
> PASS SubtleCrypto interface object length 
> PASS SubtleCrypto interface object name 
>@@ -39,29 +33,17 @@ PASS SubtleCrypto interface: existence and properties of interface prototype obj
> PASS SubtleCrypto interface: existence and properties of interface prototype object's "constructor" property 
> PASS SubtleCrypto interface: existence and properties of interface prototype object's @@unscopables property 
> PASS SubtleCrypto interface: operation encrypt(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for encrypt(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation decrypt(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for decrypt(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation sign(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for sign(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation verify(AlgorithmIdentifier, CryptoKey, BufferSource, BufferSource) 
>-PASS Unscopable handled correctly for verify(AlgorithmIdentifier, CryptoKey, BufferSource, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation digest(AlgorithmIdentifier, BufferSource) 
>-PASS Unscopable handled correctly for digest(AlgorithmIdentifier, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation generateKey(AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for generateKey(AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation deriveKey(AlgorithmIdentifier, CryptoKey, AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for deriveKey(AlgorithmIdentifier, CryptoKey, AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation deriveBits(AlgorithmIdentifier, CryptoKey, unsigned long) 
>-PASS Unscopable handled correctly for deriveBits(AlgorithmIdentifier, CryptoKey, unsigned long) on SubtleCrypto 
> PASS SubtleCrypto interface: operation importKey(KeyFormat, [object Object],[object Object], AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for importKey(KeyFormat, [object Object],[object Object], AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation exportKey(KeyFormat, CryptoKey) 
>-PASS Unscopable handled correctly for exportKey(KeyFormat, CryptoKey) on SubtleCrypto 
> PASS SubtleCrypto interface: operation wrapKey(KeyFormat, CryptoKey, CryptoKey, AlgorithmIdentifier) 
>-PASS Unscopable handled correctly for wrapKey(KeyFormat, CryptoKey, CryptoKey, AlgorithmIdentifier) on SubtleCrypto 
> PASS SubtleCrypto interface: operation unwrapKey(KeyFormat, BufferSource, CryptoKey, AlgorithmIdentifier, AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for unwrapKey(KeyFormat, BufferSource, CryptoKey, AlgorithmIdentifier, AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto must be primary interface of crypto.subtle 
> PASS Stringification of crypto.subtle 
> PASS SubtleCrypto interface: crypto.subtle must inherit property "encrypt(AlgorithmIdentifier, CryptoKey, BufferSource)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https.worker-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https.worker-expected.txt
>index 93eebaf9c6bb950352875a7f955cc10978fa0a18..ca6b6212156c32622eb463fa867424e06555fb74 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https.worker-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/WebCryptoAPI/idlharness.https.worker-expected.txt
>@@ -9,9 +9,7 @@ PASS Crypto interface: existence and properties of interface prototype object
> PASS Crypto interface: existence and properties of interface prototype object's "constructor" property 
> PASS Crypto interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Crypto interface: attribute subtle 
>-PASS Unscopable handled correctly for subtle property on Crypto 
> PASS Crypto interface: operation getRandomValues(ArrayBufferView) 
>-PASS Unscopable handled correctly for getRandomValues(ArrayBufferView) on Crypto 
> PASS Crypto must be primary interface of crypto 
> PASS Stringification of crypto 
> PASS Crypto interface: crypto must inherit property "subtle" with the proper type 
>@@ -24,13 +22,9 @@ PASS CryptoKey interface: existence and properties of interface prototype object
> PASS CryptoKey interface: existence and properties of interface prototype object's "constructor" property 
> PASS CryptoKey interface: existence and properties of interface prototype object's @@unscopables property 
> PASS CryptoKey interface: attribute type 
>-PASS Unscopable handled correctly for type property on CryptoKey 
> PASS CryptoKey interface: attribute extractable 
>-PASS Unscopable handled correctly for extractable property on CryptoKey 
> PASS CryptoKey interface: attribute algorithm 
>-PASS Unscopable handled correctly for algorithm property on CryptoKey 
> PASS CryptoKey interface: attribute usages 
>-PASS Unscopable handled correctly for usages property on CryptoKey 
> PASS SubtleCrypto interface: existence and properties of interface object 
> PASS SubtleCrypto interface object length 
> PASS SubtleCrypto interface object name 
>@@ -38,29 +32,17 @@ PASS SubtleCrypto interface: existence and properties of interface prototype obj
> PASS SubtleCrypto interface: existence and properties of interface prototype object's "constructor" property 
> PASS SubtleCrypto interface: existence and properties of interface prototype object's @@unscopables property 
> PASS SubtleCrypto interface: operation encrypt(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for encrypt(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation decrypt(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for decrypt(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation sign(AlgorithmIdentifier, CryptoKey, BufferSource) 
>-PASS Unscopable handled correctly for sign(AlgorithmIdentifier, CryptoKey, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation verify(AlgorithmIdentifier, CryptoKey, BufferSource, BufferSource) 
>-PASS Unscopable handled correctly for verify(AlgorithmIdentifier, CryptoKey, BufferSource, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation digest(AlgorithmIdentifier, BufferSource) 
>-PASS Unscopable handled correctly for digest(AlgorithmIdentifier, BufferSource) on SubtleCrypto 
> PASS SubtleCrypto interface: operation generateKey(AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for generateKey(AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation deriveKey(AlgorithmIdentifier, CryptoKey, AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for deriveKey(AlgorithmIdentifier, CryptoKey, AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation deriveBits(AlgorithmIdentifier, CryptoKey, unsigned long) 
>-PASS Unscopable handled correctly for deriveBits(AlgorithmIdentifier, CryptoKey, unsigned long) on SubtleCrypto 
> PASS SubtleCrypto interface: operation importKey(KeyFormat, [object Object],[object Object], AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for importKey(KeyFormat, [object Object],[object Object], AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto interface: operation exportKey(KeyFormat, CryptoKey) 
>-PASS Unscopable handled correctly for exportKey(KeyFormat, CryptoKey) on SubtleCrypto 
> PASS SubtleCrypto interface: operation wrapKey(KeyFormat, CryptoKey, CryptoKey, AlgorithmIdentifier) 
>-PASS Unscopable handled correctly for wrapKey(KeyFormat, CryptoKey, CryptoKey, AlgorithmIdentifier) on SubtleCrypto 
> PASS SubtleCrypto interface: operation unwrapKey(KeyFormat, BufferSource, CryptoKey, AlgorithmIdentifier, AlgorithmIdentifier, boolean, [object Object]) 
>-PASS Unscopable handled correctly for unwrapKey(KeyFormat, BufferSource, CryptoKey, AlgorithmIdentifier, AlgorithmIdentifier, boolean, [object Object]) on SubtleCrypto 
> PASS SubtleCrypto must be primary interface of crypto.subtle 
> PASS Stringification of crypto.subtle 
> PASS SubtleCrypto interface: crypto.subtle must inherit property "encrypt(AlgorithmIdentifier, CryptoKey, BufferSource)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/WebIDL/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/WebIDL/interfaces-expected.txt
>index 0a21590f266a97530454a4f94068468edbcb71f5..79d5a1e1b6a2b049967a5951672ecff45a0d3003 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/WebIDL/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/WebIDL/interfaces-expected.txt
>@@ -1,5 +1,5 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> 
> PASS Test driver 
> PASS DOMException interface: existence and properties of interface object 
>@@ -9,11 +9,8 @@ PASS DOMException interface: existence and properties of interface prototype obj
> PASS DOMException interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMException interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMException interface: attribute name 
>-PASS Unscopable handled correctly for name property on DOMException 
> PASS DOMException interface: attribute message 
>-PASS Unscopable handled correctly for message property on DOMException 
> PASS DOMException interface: attribute code 
>-PASS Unscopable handled correctly for code property on DOMException 
> PASS DOMException interface: constant INDEX_SIZE_ERR on interface object 
> PASS DOMException interface: constant INDEX_SIZE_ERR on interface prototype object 
> PASS DOMException interface: constant DOMSTRING_SIZE_ERR on interface object 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/interfaces-expected.txt
>index d72fcdaf8448dcb2e7dbec2c8d982fcb96a1804a..0a6907577b18981c6f69b9b0c55f0ad14ccefbcf 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/interfaces-expected.txt
>@@ -1,25 +1,26 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> 
> CSSOM View IDL tests
> 
> 
> PASS Test driver 
>+PASS Partial interface Window: original interface defined 
>+PASS Partial interface Document: original interface defined 
>+PASS Partial interface Element: original interface defined 
>+PASS Partial interface HTMLElement: original interface defined 
>+PASS Partial interface HTMLImageElement: original interface defined 
>+PASS Partial interface Range: original interface defined 
> PASS HTMLElement interface: attribute offsetParent 
>-PASS Unscopable handled correctly for offsetParent property on HTMLElement 
> PASS HTMLElement interface: attribute offsetTop 
>-PASS Unscopable handled correctly for offsetTop property on HTMLElement 
> PASS HTMLElement interface: attribute offsetLeft 
>-PASS Unscopable handled correctly for offsetLeft property on HTMLElement 
> PASS HTMLElement interface: attribute offsetWidth 
>-PASS Unscopable handled correctly for offsetWidth property on HTMLElement 
> PASS HTMLElement interface: attribute offsetHeight 
>-PASS Unscopable handled correctly for offsetHeight property on HTMLElement 
> PASS HTMLElement interface: document.createElement('div') must inherit property "offsetParent" with the proper type 
> PASS HTMLElement interface: document.createElement('div') must inherit property "offsetTop" with the proper type 
> PASS HTMLElement interface: document.createElement('div') must inherit property "offsetLeft" with the proper type 
>@@ -58,9 +59,7 @@ FAIL Element interface: calling convertRectFromNode(DOMRectReadOnly, GeometryNod
> FAIL Element interface: document.createElement('div') must inherit property "convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Element interface: calling convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on document.createElement('div') with too few arguments must throw TypeError assert_inherits: property "convertPointFromNode" not found in prototype chain
> PASS HTMLImageElement interface: attribute x 
>-PASS Unscopable handled correctly for x property on HTMLImageElement 
> PASS HTMLImageElement interface: attribute y 
>-PASS Unscopable handled correctly for y property on HTMLImageElement 
> PASS HTMLImageElement interface: document.createElement('img') must inherit property "x" with the proper type 
> PASS HTMLImageElement interface: document.createElement('img') must inherit property "y" with the proper type 
> PASS HTMLElement interface: document.createElement('img') must inherit property "offsetParent" with the proper type 
>@@ -101,51 +100,28 @@ FAIL Element interface: calling convertRectFromNode(DOMRectReadOnly, GeometryNod
> FAIL Element interface: document.createElement('img') must inherit property "convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Element interface: calling convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on document.createElement('img') with too few arguments must throw TypeError assert_inherits: property "convertPointFromNode" not found in prototype chain
> PASS Window interface: operation matchMedia(CSSOMString) 
>-PASS Unscopable handled correctly for matchMedia(CSSOMString) on Window 
> PASS Window interface: attribute screen 
>-PASS Unscopable handled correctly for screen property on Window 
> FAIL Window interface: operation moveTo(long, long) assert_equals: property has wrong .length expected 2 but got 0
>-PASS Unscopable handled correctly for moveTo(long, long) on Window 
> FAIL Window interface: operation moveBy(long, long) assert_equals: property has wrong .length expected 2 but got 0
>-PASS Unscopable handled correctly for moveBy(long, long) on Window 
> FAIL Window interface: operation resizeTo(long, long) assert_equals: property has wrong .length expected 2 but got 0
>-PASS Unscopable handled correctly for resizeTo(long, long) on Window 
> FAIL Window interface: operation resizeBy(long, long) assert_equals: property has wrong .length expected 2 but got 0
>-PASS Unscopable handled correctly for resizeBy(long, long) on Window 
> PASS Window interface: attribute innerWidth 
>-PASS Unscopable handled correctly for innerWidth property on Window 
> PASS Window interface: attribute innerHeight 
>-PASS Unscopable handled correctly for innerHeight property on Window 
> PASS Window interface: attribute scrollX 
>-PASS Unscopable handled correctly for scrollX property on Window 
> PASS Window interface: attribute pageXOffset 
>-PASS Unscopable handled correctly for pageXOffset property on Window 
> PASS Window interface: attribute scrollY 
>-PASS Unscopable handled correctly for scrollY property on Window 
> PASS Window interface: attribute pageYOffset 
>-PASS Unscopable handled correctly for pageYOffset property on Window 
> PASS Window interface: operation scroll(ScrollToOptions) 
>-PASS Unscopable handled correctly for scroll(ScrollToOptions) on Window 
> PASS Window interface: operation scroll(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scroll(unrestricted double, unrestricted double) on Window 
> PASS Window interface: operation scrollTo(ScrollToOptions) 
>-PASS Unscopable handled correctly for scrollTo(ScrollToOptions) on Window 
> PASS Window interface: operation scrollTo(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scrollTo(unrestricted double, unrestricted double) on Window 
> PASS Window interface: operation scrollBy(ScrollToOptions) 
>-PASS Unscopable handled correctly for scrollBy(ScrollToOptions) on Window 
> PASS Window interface: operation scrollBy(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scrollBy(unrestricted double, unrestricted double) on Window 
> PASS Window interface: attribute screenX 
>-PASS Unscopable handled correctly for screenX property on Window 
> PASS Window interface: attribute screenY 
>-PASS Unscopable handled correctly for screenY property on Window 
> PASS Window interface: attribute outerWidth 
>-PASS Unscopable handled correctly for outerWidth property on Window 
> PASS Window interface: attribute outerHeight 
>-PASS Unscopable handled correctly for outerHeight property on Window 
> PASS Window interface: attribute devicePixelRatio 
>-PASS Unscopable handled correctly for devicePixelRatio property on Window 
> PASS Window interface: window must inherit property "matchMedia(CSSOMString)" with the proper type 
> PASS Window interface: calling matchMedia(CSSOMString) on window with too few arguments must throw TypeError 
> PASS Window interface: window must inherit property "screen" with the proper type 
>@@ -194,21 +170,13 @@ PASS SharedWorkerGlobalScope interface: existence and properties of interface ob
> PASS WorkerNavigator interface: existence and properties of interface object 
> PASS WorkerLocation interface: existence and properties of interface object 
> PASS Document interface: operation elementFromPoint(double, double) 
>-PASS Unscopable handled correctly for elementFromPoint(double, double) on Document 
> PASS Document interface: operation elementsFromPoint(double, double) 
>-PASS Unscopable handled correctly for elementsFromPoint(double, double) on Document 
> FAIL Document interface: operation caretPositionFromPoint(double, double) assert_own_property: interface prototype object missing non-static operation expected property "caretPositionFromPoint" missing
>-PASS Unscopable handled correctly for caretPositionFromPoint(double, double) on Document 
> PASS Document interface: attribute scrollingElement 
>-PASS Unscopable handled correctly for scrollingElement property on Document 
> FAIL Document interface: operation getBoxQuads(BoxQuadOptions) assert_own_property: interface prototype object missing non-static operation expected property "getBoxQuads" missing
>-PASS Unscopable handled correctly for getBoxQuads(BoxQuadOptions) on Document 
> FAIL Document interface: operation convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertQuadFromNode" missing
>-PASS Unscopable handled correctly for convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) on Document 
> FAIL Document interface: operation convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertRectFromNode" missing
>-PASS Unscopable handled correctly for convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) on Document 
> FAIL Document interface: operation convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertPointFromNode" missing
>-PASS Unscopable handled correctly for convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on Document 
> PASS Document interface: document must inherit property "elementFromPoint(double, double)" with the proper type 
> PASS Document interface: calling elementFromPoint(double, double) on document with too few arguments must throw TypeError 
> PASS Document interface: document must inherit property "elementsFromPoint(double, double)" with the proper type 
>@@ -225,47 +193,26 @@ FAIL Document interface: calling convertRectFromNode(DOMRectReadOnly, GeometryNo
> FAIL Document interface: document must inherit property "convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Document interface: calling convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on document with too few arguments must throw TypeError assert_inherits: property "convertPointFromNode" not found in prototype chain
> PASS Element interface: operation getClientRects() 
>-PASS Unscopable handled correctly for getClientRects() on Element 
> PASS Element interface: operation getBoundingClientRect() 
>-PASS Unscopable handled correctly for getBoundingClientRect() on Element 
> PASS Element interface: operation scrollIntoView([object Object],[object Object]) 
>-PASS Unscopable handled correctly for scrollIntoView([object Object],[object Object]) on Element 
> PASS Element interface: operation scroll(ScrollToOptions) 
>-PASS Unscopable handled correctly for scroll(ScrollToOptions) on Element 
> PASS Element interface: operation scroll(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scroll(unrestricted double, unrestricted double) on Element 
> PASS Element interface: operation scrollTo(ScrollToOptions) 
>-PASS Unscopable handled correctly for scrollTo(ScrollToOptions) on Element 
> PASS Element interface: operation scrollTo(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scrollTo(unrestricted double, unrestricted double) on Element 
> PASS Element interface: operation scrollBy(ScrollToOptions) 
>-PASS Unscopable handled correctly for scrollBy(ScrollToOptions) on Element 
> PASS Element interface: operation scrollBy(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scrollBy(unrestricted double, unrestricted double) on Element 
> PASS Element interface: attribute scrollTop 
>-PASS Unscopable handled correctly for scrollTop property on Element 
> PASS Element interface: attribute scrollLeft 
>-PASS Unscopable handled correctly for scrollLeft property on Element 
> PASS Element interface: attribute scrollWidth 
>-PASS Unscopable handled correctly for scrollWidth property on Element 
> PASS Element interface: attribute scrollHeight 
>-PASS Unscopable handled correctly for scrollHeight property on Element 
> PASS Element interface: attribute clientTop 
>-PASS Unscopable handled correctly for clientTop property on Element 
> PASS Element interface: attribute clientLeft 
>-PASS Unscopable handled correctly for clientLeft property on Element 
> PASS Element interface: attribute clientWidth 
>-PASS Unscopable handled correctly for clientWidth property on Element 
> PASS Element interface: attribute clientHeight 
>-PASS Unscopable handled correctly for clientHeight property on Element 
> FAIL Element interface: operation getBoxQuads(BoxQuadOptions) assert_own_property: interface prototype object missing non-static operation expected property "getBoxQuads" missing
>-PASS Unscopable handled correctly for getBoxQuads(BoxQuadOptions) on Element 
> FAIL Element interface: operation convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertQuadFromNode" missing
>-PASS Unscopable handled correctly for convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) on Element 
> FAIL Element interface: operation convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertRectFromNode" missing
>-PASS Unscopable handled correctly for convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) on Element 
> FAIL Element interface: operation convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertPointFromNode" missing
>-PASS Unscopable handled correctly for convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on Element 
> PASS Element interface: document.createElementNS('x', 'y') must inherit property "getClientRects()" with the proper type 
> PASS Element interface: document.createElementNS('x', 'y') must inherit property "getBoundingClientRect()" with the proper type 
> PASS Element interface: document.createElementNS('x', 'y') must inherit property "scrollIntoView([object Object],[object Object])" with the proper type 
>@@ -299,13 +246,9 @@ FAIL Element interface: calling convertRectFromNode(DOMRectReadOnly, GeometryNod
> FAIL Element interface: document.createElementNS('x', 'y') must inherit property "convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Element interface: calling convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on document.createElementNS('x', 'y') with too few arguments must throw TypeError assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Text interface: operation getBoxQuads(BoxQuadOptions) assert_own_property: interface prototype object missing non-static operation expected property "getBoxQuads" missing
>-PASS Unscopable handled correctly for getBoxQuads(BoxQuadOptions) on Text 
> FAIL Text interface: operation convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertQuadFromNode" missing
>-PASS Unscopable handled correctly for convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions) on Text 
> FAIL Text interface: operation convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertRectFromNode" missing
>-PASS Unscopable handled correctly for convertRectFromNode(DOMRectReadOnly, GeometryNode, ConvertCoordinateOptions) on Text 
> FAIL Text interface: operation convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) assert_own_property: interface prototype object missing non-static operation expected property "convertPointFromNode" missing
>-PASS Unscopable handled correctly for convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on Text 
> FAIL Text interface: document.createTextNode('x') must inherit property "getBoxQuads(BoxQuadOptions)" with the proper type assert_inherits: property "getBoxQuads" not found in prototype chain
> FAIL Text interface: calling getBoxQuads(BoxQuadOptions) on document.createTextNode('x') with too few arguments must throw TypeError assert_inherits: property "getBoxQuads" not found in prototype chain
> FAIL Text interface: document.createTextNode('x') must inherit property "convertQuadFromNode(DOMQuadInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertQuadFromNode" not found in prototype chain
>@@ -315,9 +258,7 @@ FAIL Text interface: calling convertRectFromNode(DOMRectReadOnly, GeometryNode,
> FAIL Text interface: document.createTextNode('x') must inherit property "convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions)" with the proper type assert_inherits: property "convertPointFromNode" not found in prototype chain
> FAIL Text interface: calling convertPointFromNode(DOMPointInit, GeometryNode, ConvertCoordinateOptions) on document.createTextNode('x') with too few arguments must throw TypeError assert_inherits: property "convertPointFromNode" not found in prototype chain
> PASS Range interface: operation getClientRects() 
>-PASS Unscopable handled correctly for getClientRects() on Range 
> PASS Range interface: operation getBoundingClientRect() 
>-PASS Unscopable handled correctly for getBoundingClientRect() on Range 
> PASS Range interface: new Range() must inherit property "getClientRects()" with the proper type 
> PASS Range interface: new Range() must inherit property "getBoundingClientRect()" with the proper type 
> FAIL MediaQueryList interface: existence and properties of interface object assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>@@ -327,15 +268,10 @@ FAIL MediaQueryList interface: existence and properties of interface prototype o
> FAIL MediaQueryList interface: existence and properties of interface prototype object's "constructor" property assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
> FAIL MediaQueryList interface: existence and properties of interface prototype object's @@unscopables property assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
> FAIL MediaQueryList interface: attribute media assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>-PASS Unscopable handled correctly for media property on MediaQueryList 
> FAIL MediaQueryList interface: attribute matches assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>-PASS Unscopable handled correctly for matches property on MediaQueryList 
> FAIL MediaQueryList interface: operation addListener(EventListener) assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>-PASS Unscopable handled correctly for addListener(EventListener) on MediaQueryList 
> FAIL MediaQueryList interface: operation removeListener(EventListener) assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>-PASS Unscopable handled correctly for removeListener(EventListener) on MediaQueryList 
> FAIL MediaQueryList interface: attribute onchange assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
>-PASS Unscopable handled correctly for onchange property on MediaQueryList 
> FAIL MediaQueryList must be primary interface of matchMedia('all') assert_own_property: self does not have own property "MediaQueryList" expected property "MediaQueryList" missing
> PASS Stringification of matchMedia('all') 
> PASS MediaQueryList interface: matchMedia('all') must inherit property "media" with the proper type 
>@@ -356,9 +292,7 @@ FAIL MediaQueryListEvent interface: existence and properties of interface protot
> FAIL MediaQueryListEvent interface: existence and properties of interface prototype object's "constructor" property assert_own_property: self does not have own property "MediaQueryListEvent" expected property "MediaQueryListEvent" missing
> FAIL MediaQueryListEvent interface: existence and properties of interface prototype object's @@unscopables property assert_own_property: self does not have own property "MediaQueryListEvent" expected property "MediaQueryListEvent" missing
> FAIL MediaQueryListEvent interface: attribute media assert_own_property: self does not have own property "MediaQueryListEvent" expected property "MediaQueryListEvent" missing
>-PASS Unscopable handled correctly for media property on MediaQueryListEvent 
> FAIL MediaQueryListEvent interface: attribute matches assert_own_property: self does not have own property "MediaQueryListEvent" expected property "MediaQueryListEvent" missing
>-PASS Unscopable handled correctly for matches property on MediaQueryListEvent 
> FAIL MediaQueryListEvent must be primary interface of new MediaQueryListEvent('change') assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: MediaQueryListEvent"
> FAIL Stringification of new MediaQueryListEvent('change') assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: MediaQueryListEvent"
> FAIL MediaQueryListEvent interface: new MediaQueryListEvent('change') must inherit property "media" with the proper type assert_equals: Unexpected exception when evaluating object expected null but got object "ReferenceError: Can't find variable: MediaQueryListEvent"
>@@ -370,17 +304,11 @@ PASS Screen interface: existence and properties of interface prototype object
> PASS Screen interface: existence and properties of interface prototype object's "constructor" property 
> PASS Screen interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Screen interface: attribute availWidth 
>-PASS Unscopable handled correctly for availWidth property on Screen 
> PASS Screen interface: attribute availHeight 
>-PASS Unscopable handled correctly for availHeight property on Screen 
> PASS Screen interface: attribute width 
>-PASS Unscopable handled correctly for width property on Screen 
> PASS Screen interface: attribute height 
>-PASS Unscopable handled correctly for height property on Screen 
> PASS Screen interface: attribute colorDepth 
>-PASS Unscopable handled correctly for colorDepth property on Screen 
> PASS Screen interface: attribute pixelDepth 
>-PASS Unscopable handled correctly for pixelDepth property on Screen 
> PASS Screen must be primary interface of screen 
> PASS Stringification of screen 
> PASS Screen interface: screen must inherit property "availWidth" with the proper type 
>@@ -396,11 +324,8 @@ FAIL CaretPosition interface: existence and properties of interface prototype ob
> FAIL CaretPosition interface: existence and properties of interface prototype object's "constructor" property assert_own_property: self does not have own property "CaretPosition" expected property "CaretPosition" missing
> FAIL CaretPosition interface: existence and properties of interface prototype object's @@unscopables property assert_own_property: self does not have own property "CaretPosition" expected property "CaretPosition" missing
> FAIL CaretPosition interface: attribute offsetNode assert_own_property: self does not have own property "CaretPosition" expected property "CaretPosition" missing
>-PASS Unscopable handled correctly for offsetNode property on CaretPosition 
> FAIL CaretPosition interface: attribute offset assert_own_property: self does not have own property "CaretPosition" expected property "CaretPosition" missing
>-PASS Unscopable handled correctly for offset property on CaretPosition 
> FAIL CaretPosition interface: operation getClientRect() assert_own_property: self does not have own property "CaretPosition" expected property "CaretPosition" missing
>-PASS Unscopable handled correctly for getClientRect() on CaretPosition 
> FAIL CaretPosition must be primary interface of document.caretPositionFromPoint(5, 5) assert_equals: Unexpected exception when evaluating object expected null but got object "TypeError: document.caretPositionFromPoint is not a function. (In 'document.caretPositionFromPoint(5, 5)', 'document.caretPositionFromPoint' is undefined)"
> FAIL Stringification of document.caretPositionFromPoint(5, 5) assert_equals: Unexpected exception when evaluating object expected null but got object "TypeError: document.caretPositionFromPoint is not a function. (In 'document.caretPositionFromPoint(5, 5)', 'document.caretPositionFromPoint' is undefined)"
> FAIL CaretPosition interface: document.caretPositionFromPoint(5, 5) must inherit property "offsetNode" with the proper type assert_equals: Unexpected exception when evaluating object expected null but got object "TypeError: document.caretPositionFromPoint is not a function. (In 'document.caretPositionFromPoint(5, 5)', 'document.caretPositionFromPoint' is undefined)"
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces-expected.txt
>index c899a3189b84833295d754cb04f41d96606d58e2..fa635df434401137b9b5103d1d44ebbe30b5bd38 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces-expected.txt
>@@ -7,19 +7,12 @@ PASS DOMPointReadOnly interface: existence and properties of interface prototype
> PASS DOMPointReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMPointReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMPointReadOnly interface: operation fromPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for fromPoint(DOMPointInit) on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute z 
>-PASS Unscopable handled correctly for z property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute w 
>-PASS Unscopable handled correctly for w property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: operation matrixTransform(DOMMatrixInit) 
>-PASS Unscopable handled correctly for matrixTransform(DOMMatrixInit) on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMPointReadOnly 
> PASS DOMPointReadOnly must be primary interface of new DOMPointReadOnly() 
> PASS Stringification of new DOMPointReadOnly() 
> PASS DOMPointReadOnly interface: new DOMPointReadOnly() must inherit property "fromPoint(DOMPointInit)" with the proper type 
>@@ -44,15 +37,10 @@ PASS DOMPoint interface: existence and properties of interface prototype object
> PASS DOMPoint interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMPoint interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMPoint interface: operation fromPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for fromPoint(DOMPointInit) on DOMPoint 
> PASS DOMPoint interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMPoint 
> PASS DOMPoint interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMPoint 
> PASS DOMPoint interface: attribute z 
>-PASS Unscopable handled correctly for z property on DOMPoint 
> PASS DOMPoint interface: attribute w 
>-PASS Unscopable handled correctly for w property on DOMPoint 
> PASS DOMPoint must be primary interface of new DOMPoint() 
> PASS Stringification of new DOMPoint() 
> PASS DOMPoint interface: new DOMPoint() must inherit property "fromPoint(DOMPointInit)" with the proper type 
>@@ -78,25 +66,15 @@ PASS DOMRectReadOnly interface: existence and properties of interface prototype
> PASS DOMRectReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMRectReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMRectReadOnly interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute width 
>-PASS Unscopable handled correctly for width property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute height 
>-PASS Unscopable handled correctly for height property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute top 
>-PASS Unscopable handled correctly for top property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute right 
>-PASS Unscopable handled correctly for right property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute bottom 
>-PASS Unscopable handled correctly for bottom property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute left 
>-PASS Unscopable handled correctly for left property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMRectReadOnly 
> PASS DOMRectReadOnly must be primary interface of new DOMRectReadOnly() 
> PASS Stringification of new DOMRectReadOnly() 
> PASS DOMRectReadOnly interface: new DOMRectReadOnly() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -123,15 +101,10 @@ PASS DOMRect interface: existence and properties of interface prototype object
> PASS DOMRect interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMRect interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMRect interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMRect 
> PASS DOMRect interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMRect 
> PASS DOMRect interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMRect 
> PASS DOMRect interface: attribute width 
>-PASS Unscopable handled correctly for width property on DOMRect 
> PASS DOMRect interface: attribute height 
>-PASS Unscopable handled correctly for height property on DOMRect 
> PASS DOMRect must be primary interface of new DOMRect() 
> PASS Stringification of new DOMRect() 
> PASS DOMRect interface: new DOMRect() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -159,9 +132,7 @@ PASS DOMRectList interface: existence and properties of interface prototype obje
> PASS DOMRectList interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMRectList interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMRectList interface: attribute length 
>-PASS Unscopable handled correctly for length property on DOMRectList 
> PASS DOMRectList interface: operation item(unsigned long) 
>-PASS Unscopable handled correctly for item(unsigned long) on DOMRectList 
> PASS DOMRectList must be primary interface of [object DOMRectList] 
> PASS Stringification of [object DOMRectList] 
> PASS DOMRectList interface: [object DOMRectList] must inherit property "length" with the proper type 
>@@ -174,21 +145,13 @@ PASS DOMQuad interface: existence and properties of interface prototype object
> PASS DOMQuad interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMQuad interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMQuad interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMQuad 
> PASS DOMQuad interface: operation fromQuad(DOMQuadInit) 
>-PASS Unscopable handled correctly for fromQuad(DOMQuadInit) on DOMQuad 
> PASS DOMQuad interface: attribute p1 
>-PASS Unscopable handled correctly for p1 property on DOMQuad 
> PASS DOMQuad interface: attribute p2 
>-PASS Unscopable handled correctly for p2 property on DOMQuad 
> PASS DOMQuad interface: attribute p3 
>-PASS Unscopable handled correctly for p3 property on DOMQuad 
> PASS DOMQuad interface: attribute p4 
>-PASS Unscopable handled correctly for p4 property on DOMQuad 
> PASS DOMQuad interface: operation getBounds() 
>-PASS Unscopable handled correctly for getBounds() on DOMQuad 
> PASS DOMQuad interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMQuad 
> PASS DOMQuad must be primary interface of new DOMQuad() 
> PASS Stringification of new DOMQuad() 
> PASS DOMQuad interface: new DOMQuad() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -209,92 +172,49 @@ PASS DOMMatrixReadOnly interface: existence and properties of interface prototyp
> PASS DOMMatrixReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMMatrixReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMMatrixReadOnly interface: operation fromMatrix(DOMMatrixInit) 
>-PASS Unscopable handled correctly for fromMatrix(DOMMatrixInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation fromFloat32Array(Float32Array) 
>-PASS Unscopable handled correctly for fromFloat32Array(Float32Array) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation fromFloat64Array(Float64Array) 
>-PASS Unscopable handled correctly for fromFloat64Array(Float64Array) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute a 
>-PASS Unscopable handled correctly for a property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute b 
>-PASS Unscopable handled correctly for b property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute c 
>-PASS Unscopable handled correctly for c property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute d 
>-PASS Unscopable handled correctly for d property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute e 
>-PASS Unscopable handled correctly for e property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute f 
>-PASS Unscopable handled correctly for f property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m11 
>-PASS Unscopable handled correctly for m11 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m12 
>-PASS Unscopable handled correctly for m12 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m13 
>-PASS Unscopable handled correctly for m13 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m14 
>-PASS Unscopable handled correctly for m14 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m21 
>-PASS Unscopable handled correctly for m21 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m22 
>-PASS Unscopable handled correctly for m22 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m23 
>-PASS Unscopable handled correctly for m23 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m24 
>-PASS Unscopable handled correctly for m24 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m31 
>-PASS Unscopable handled correctly for m31 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m32 
>-PASS Unscopable handled correctly for m32 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m33 
>-PASS Unscopable handled correctly for m33 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m34 
>-PASS Unscopable handled correctly for m34 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m41 
>-PASS Unscopable handled correctly for m41 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m42 
>-PASS Unscopable handled correctly for m42 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m43 
>-PASS Unscopable handled correctly for m43 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m44 
>-PASS Unscopable handled correctly for m44 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute is2D 
>-PASS Unscopable handled correctly for is2D property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute isIdentity 
>-PASS Unscopable handled correctly for isIdentity property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation translate(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for translate(unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation scale(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation scale3d(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale3d(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotate(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotate(unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotateFromVector(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateFromVector(unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotateAxisAngle(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateAxisAngle(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation skewX(unrestricted double) 
>-PASS Unscopable handled correctly for skewX(unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation skewY(unrestricted double) 
>-PASS Unscopable handled correctly for skewY(unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation multiply(DOMMatrixInit) 
>-PASS Unscopable handled correctly for multiply(DOMMatrixInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation flipX() 
>-PASS Unscopable handled correctly for flipX() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation flipY() 
>-PASS Unscopable handled correctly for flipY() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation inverse() 
>-PASS Unscopable handled correctly for inverse() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation transformPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for transformPoint(DOMPointInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation toFloat32Array() 
>-PASS Unscopable handled correctly for toFloat32Array() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation toFloat64Array() 
>-PASS Unscopable handled correctly for toFloat64Array() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: stringifier 
> PASS DOMMatrixReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly must be primary interface of new DOMMatrixReadOnly() 
> PASS Stringification of new DOMMatrixReadOnly() 
> PASS DOMMatrixReadOnly interface: new DOMMatrixReadOnly() must inherit property "fromMatrix(DOMMatrixInit)" with the proper type 
>@@ -368,79 +288,42 @@ PASS DOMMatrix interface: existence and properties of interface prototype object
> PASS DOMMatrix interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMMatrix interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMMatrix interface: operation fromMatrix(DOMMatrixInit) 
>-PASS Unscopable handled correctly for fromMatrix(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation fromFloat32Array(Float32Array) 
>-PASS Unscopable handled correctly for fromFloat32Array(Float32Array) on DOMMatrix 
> PASS DOMMatrix interface: operation fromFloat64Array(Float64Array) 
>-PASS Unscopable handled correctly for fromFloat64Array(Float64Array) on DOMMatrix 
> PASS DOMMatrix interface: attribute a 
>-PASS Unscopable handled correctly for a property on DOMMatrix 
> PASS DOMMatrix interface: attribute b 
>-PASS Unscopable handled correctly for b property on DOMMatrix 
> PASS DOMMatrix interface: attribute c 
>-PASS Unscopable handled correctly for c property on DOMMatrix 
> PASS DOMMatrix interface: attribute d 
>-PASS Unscopable handled correctly for d property on DOMMatrix 
> PASS DOMMatrix interface: attribute e 
>-PASS Unscopable handled correctly for e property on DOMMatrix 
> PASS DOMMatrix interface: attribute f 
>-PASS Unscopable handled correctly for f property on DOMMatrix 
> PASS DOMMatrix interface: attribute m11 
>-PASS Unscopable handled correctly for m11 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m12 
>-PASS Unscopable handled correctly for m12 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m13 
>-PASS Unscopable handled correctly for m13 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m14 
>-PASS Unscopable handled correctly for m14 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m21 
>-PASS Unscopable handled correctly for m21 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m22 
>-PASS Unscopable handled correctly for m22 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m23 
>-PASS Unscopable handled correctly for m23 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m24 
>-PASS Unscopable handled correctly for m24 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m31 
>-PASS Unscopable handled correctly for m31 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m32 
>-PASS Unscopable handled correctly for m32 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m33 
>-PASS Unscopable handled correctly for m33 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m34 
>-PASS Unscopable handled correctly for m34 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m41 
>-PASS Unscopable handled correctly for m41 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m42 
>-PASS Unscopable handled correctly for m42 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m43 
>-PASS Unscopable handled correctly for m43 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m44 
>-PASS Unscopable handled correctly for m44 property on DOMMatrix 
> PASS DOMMatrix interface: operation multiplySelf(DOMMatrixInit) 
>-PASS Unscopable handled correctly for multiplySelf(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation preMultiplySelf(DOMMatrixInit) 
>-PASS Unscopable handled correctly for preMultiplySelf(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation translateSelf(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for translateSelf(unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation scaleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scaleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation scale3dSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale3dSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateSelf(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateSelf(unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateFromVectorSelf(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateFromVectorSelf(unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateAxisAngleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateAxisAngleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation skewXSelf(unrestricted double) 
>-PASS Unscopable handled correctly for skewXSelf(unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation skewYSelf(unrestricted double) 
>-PASS Unscopable handled correctly for skewYSelf(unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation invertSelf() 
>-PASS Unscopable handled correctly for invertSelf() on DOMMatrix 
> PASS DOMMatrix interface: operation setMatrixValue(DOMString) 
>-PASS Unscopable handled correctly for setMatrixValue(DOMString) on DOMMatrix 
> PASS DOMMatrix must be primary interface of new DOMMatrix() 
> PASS Stringification of new DOMMatrix() 
> PASS DOMMatrix interface: new DOMMatrix() must inherit property "fromMatrix(DOMMatrixInit)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces.worker-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces.worker-expected.txt
>index 81ca4b8cfe106fa13466d8b06001ba15491bc6eb..90587082502fb0387b2ed4ececfa06ad7c104f88 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces.worker-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/geometry/interfaces.worker-expected.txt
>@@ -7,19 +7,12 @@ PASS DOMPointReadOnly interface: existence and properties of interface prototype
> PASS DOMPointReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMPointReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMPointReadOnly interface: operation fromPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for fromPoint(DOMPointInit) on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute z 
>-PASS Unscopable handled correctly for z property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: attribute w 
>-PASS Unscopable handled correctly for w property on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: operation matrixTransform(DOMMatrixInit) 
>-PASS Unscopable handled correctly for matrixTransform(DOMMatrixInit) on DOMPointReadOnly 
> PASS DOMPointReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMPointReadOnly 
> PASS DOMPointReadOnly must be primary interface of new DOMPointReadOnly() 
> PASS Stringification of new DOMPointReadOnly() 
> PASS DOMPointReadOnly interface: new DOMPointReadOnly() must inherit property "fromPoint(DOMPointInit)" with the proper type 
>@@ -40,15 +33,10 @@ PASS DOMPoint interface: existence and properties of interface prototype object
> PASS DOMPoint interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMPoint interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMPoint interface: operation fromPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for fromPoint(DOMPointInit) on DOMPoint 
> PASS DOMPoint interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMPoint 
> PASS DOMPoint interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMPoint 
> PASS DOMPoint interface: attribute z 
>-PASS Unscopable handled correctly for z property on DOMPoint 
> PASS DOMPoint interface: attribute w 
>-PASS Unscopable handled correctly for w property on DOMPoint 
> PASS DOMPoint must be primary interface of new DOMPoint() 
> PASS Stringification of new DOMPoint() 
> PASS DOMPoint interface: new DOMPoint() must inherit property "fromPoint(DOMPointInit)" with the proper type 
>@@ -74,25 +62,15 @@ PASS DOMRectReadOnly interface: existence and properties of interface prototype
> PASS DOMRectReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMRectReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMRectReadOnly interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute width 
>-PASS Unscopable handled correctly for width property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute height 
>-PASS Unscopable handled correctly for height property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute top 
>-PASS Unscopable handled correctly for top property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute right 
>-PASS Unscopable handled correctly for right property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute bottom 
>-PASS Unscopable handled correctly for bottom property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: attribute left 
>-PASS Unscopable handled correctly for left property on DOMRectReadOnly 
> PASS DOMRectReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMRectReadOnly 
> PASS DOMRectReadOnly must be primary interface of new DOMRectReadOnly() 
> PASS Stringification of new DOMRectReadOnly() 
> PASS DOMRectReadOnly interface: new DOMRectReadOnly() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -115,15 +93,10 @@ PASS DOMRect interface: existence and properties of interface prototype object
> PASS DOMRect interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMRect interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMRect interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMRect 
> PASS DOMRect interface: attribute x 
>-PASS Unscopable handled correctly for x property on DOMRect 
> PASS DOMRect interface: attribute y 
>-PASS Unscopable handled correctly for y property on DOMRect 
> PASS DOMRect interface: attribute width 
>-PASS Unscopable handled correctly for width property on DOMRect 
> PASS DOMRect interface: attribute height 
>-PASS Unscopable handled correctly for height property on DOMRect 
> PASS DOMRect must be primary interface of new DOMRect() 
> PASS Stringification of new DOMRect() 
> PASS DOMRect interface: new DOMRect() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -152,21 +125,13 @@ PASS DOMQuad interface: existence and properties of interface prototype object
> PASS DOMQuad interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMQuad interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMQuad interface: operation fromRect(DOMRectInit) 
>-PASS Unscopable handled correctly for fromRect(DOMRectInit) on DOMQuad 
> PASS DOMQuad interface: operation fromQuad(DOMQuadInit) 
>-PASS Unscopable handled correctly for fromQuad(DOMQuadInit) on DOMQuad 
> PASS DOMQuad interface: attribute p1 
>-PASS Unscopable handled correctly for p1 property on DOMQuad 
> PASS DOMQuad interface: attribute p2 
>-PASS Unscopable handled correctly for p2 property on DOMQuad 
> PASS DOMQuad interface: attribute p3 
>-PASS Unscopable handled correctly for p3 property on DOMQuad 
> PASS DOMQuad interface: attribute p4 
>-PASS Unscopable handled correctly for p4 property on DOMQuad 
> PASS DOMQuad interface: operation getBounds() 
>-PASS Unscopable handled correctly for getBounds() on DOMQuad 
> PASS DOMQuad interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMQuad 
> PASS DOMQuad must be primary interface of new DOMQuad() 
> PASS Stringification of new DOMQuad() 
> PASS DOMQuad interface: new DOMQuad() must inherit property "fromRect(DOMRectInit)" with the proper type 
>@@ -187,92 +152,49 @@ PASS DOMMatrixReadOnly interface: existence and properties of interface prototyp
> PASS DOMMatrixReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMMatrixReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMMatrixReadOnly interface: operation fromMatrix(DOMMatrixInit) 
>-PASS Unscopable handled correctly for fromMatrix(DOMMatrixInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation fromFloat32Array(Float32Array) 
>-PASS Unscopable handled correctly for fromFloat32Array(Float32Array) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation fromFloat64Array(Float64Array) 
>-PASS Unscopable handled correctly for fromFloat64Array(Float64Array) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute a 
>-PASS Unscopable handled correctly for a property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute b 
>-PASS Unscopable handled correctly for b property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute c 
>-PASS Unscopable handled correctly for c property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute d 
>-PASS Unscopable handled correctly for d property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute e 
>-PASS Unscopable handled correctly for e property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute f 
>-PASS Unscopable handled correctly for f property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m11 
>-PASS Unscopable handled correctly for m11 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m12 
>-PASS Unscopable handled correctly for m12 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m13 
>-PASS Unscopable handled correctly for m13 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m14 
>-PASS Unscopable handled correctly for m14 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m21 
>-PASS Unscopable handled correctly for m21 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m22 
>-PASS Unscopable handled correctly for m22 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m23 
>-PASS Unscopable handled correctly for m23 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m24 
>-PASS Unscopable handled correctly for m24 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m31 
>-PASS Unscopable handled correctly for m31 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m32 
>-PASS Unscopable handled correctly for m32 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m33 
>-PASS Unscopable handled correctly for m33 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m34 
>-PASS Unscopable handled correctly for m34 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m41 
>-PASS Unscopable handled correctly for m41 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m42 
>-PASS Unscopable handled correctly for m42 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m43 
>-PASS Unscopable handled correctly for m43 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute m44 
>-PASS Unscopable handled correctly for m44 property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute is2D 
>-PASS Unscopable handled correctly for is2D property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: attribute isIdentity 
>-PASS Unscopable handled correctly for isIdentity property on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation translate(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for translate(unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation scale(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation scale3d(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale3d(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotate(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotate(unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotateFromVector(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateFromVector(unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation rotateAxisAngle(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateAxisAngle(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation skewX(unrestricted double) 
>-PASS Unscopable handled correctly for skewX(unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation skewY(unrestricted double) 
>-PASS Unscopable handled correctly for skewY(unrestricted double) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation multiply(DOMMatrixInit) 
>-PASS Unscopable handled correctly for multiply(DOMMatrixInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation flipX() 
>-PASS Unscopable handled correctly for flipX() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation flipY() 
>-PASS Unscopable handled correctly for flipY() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation inverse() 
>-PASS Unscopable handled correctly for inverse() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation transformPoint(DOMPointInit) 
>-PASS Unscopable handled correctly for transformPoint(DOMPointInit) on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation toFloat32Array() 
>-PASS Unscopable handled correctly for toFloat32Array() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: operation toFloat64Array() 
>-PASS Unscopable handled correctly for toFloat64Array() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly interface: member undefined 
> PASS DOMMatrixReadOnly interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on DOMMatrixReadOnly 
> PASS DOMMatrixReadOnly must be primary interface of new DOMMatrixReadOnly() 
> PASS Stringification of new DOMMatrixReadOnly() 
> PASS DOMMatrixReadOnly interface: new DOMMatrixReadOnly() must inherit property "fromMatrix(DOMMatrixInit)" with the proper type 
>@@ -343,77 +265,41 @@ PASS DOMMatrix interface: existence and properties of interface prototype object
> PASS DOMMatrix interface: existence and properties of interface prototype object's "constructor" property 
> PASS DOMMatrix interface: existence and properties of interface prototype object's @@unscopables property 
> PASS DOMMatrix interface: operation fromMatrix(DOMMatrixInit) 
>-PASS Unscopable handled correctly for fromMatrix(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation fromFloat32Array(Float32Array) 
>-PASS Unscopable handled correctly for fromFloat32Array(Float32Array) on DOMMatrix 
> PASS DOMMatrix interface: operation fromFloat64Array(Float64Array) 
>-PASS Unscopable handled correctly for fromFloat64Array(Float64Array) on DOMMatrix 
> PASS DOMMatrix interface: attribute a 
>-PASS Unscopable handled correctly for a property on DOMMatrix 
> PASS DOMMatrix interface: attribute b 
>-PASS Unscopable handled correctly for b property on DOMMatrix 
> PASS DOMMatrix interface: attribute c 
>-PASS Unscopable handled correctly for c property on DOMMatrix 
> PASS DOMMatrix interface: attribute d 
>-PASS Unscopable handled correctly for d property on DOMMatrix 
> PASS DOMMatrix interface: attribute e 
>-PASS Unscopable handled correctly for e property on DOMMatrix 
> PASS DOMMatrix interface: attribute f 
>-PASS Unscopable handled correctly for f property on DOMMatrix 
> PASS DOMMatrix interface: attribute m11 
>-PASS Unscopable handled correctly for m11 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m12 
>-PASS Unscopable handled correctly for m12 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m13 
>-PASS Unscopable handled correctly for m13 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m14 
>-PASS Unscopable handled correctly for m14 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m21 
>-PASS Unscopable handled correctly for m21 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m22 
>-PASS Unscopable handled correctly for m22 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m23 
>-PASS Unscopable handled correctly for m23 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m24 
>-PASS Unscopable handled correctly for m24 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m31 
>-PASS Unscopable handled correctly for m31 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m32 
>-PASS Unscopable handled correctly for m32 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m33 
>-PASS Unscopable handled correctly for m33 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m34 
>-PASS Unscopable handled correctly for m34 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m41 
>-PASS Unscopable handled correctly for m41 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m42 
>-PASS Unscopable handled correctly for m42 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m43 
>-PASS Unscopable handled correctly for m43 property on DOMMatrix 
> PASS DOMMatrix interface: attribute m44 
>-PASS Unscopable handled correctly for m44 property on DOMMatrix 
> PASS DOMMatrix interface: operation multiplySelf(DOMMatrixInit) 
>-PASS Unscopable handled correctly for multiplySelf(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation preMultiplySelf(DOMMatrixInit) 
>-PASS Unscopable handled correctly for preMultiplySelf(DOMMatrixInit) on DOMMatrix 
> PASS DOMMatrix interface: operation translateSelf(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for translateSelf(unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation scaleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scaleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation scale3dSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for scale3dSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateSelf(unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateSelf(unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateFromVectorSelf(unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateFromVectorSelf(unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation rotateAxisAngleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) 
>-PASS Unscopable handled correctly for rotateAxisAngleSelf(unrestricted double, unrestricted double, unrestricted double, unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation skewXSelf(unrestricted double) 
>-PASS Unscopable handled correctly for skewXSelf(unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation skewYSelf(unrestricted double) 
>-PASS Unscopable handled correctly for skewYSelf(unrestricted double) on DOMMatrix 
> PASS DOMMatrix interface: operation invertSelf() 
>-PASS Unscopable handled correctly for invertSelf() on DOMMatrix 
> PASS DOMMatrix interface: member setMatrixValue 
> PASS DOMMatrix must be primary interface of new DOMMatrix() 
> PASS Stringification of new DOMMatrix() 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/dom/interfaces.html b/LayoutTests/imported/w3c/web-platform-tests/dom/interfaces.html
>index 3cb08f405a5a768c26c0c1f25d3d6d32ea9beb77..c0fab016ae75b733a17da29e176f28e6cec243b7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/dom/interfaces.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/dom/interfaces.html
>@@ -19,11 +19,8 @@ element.setAttribute("bar", "baz");
> var idlArray = new IdlArray();
> 
> function doTest([html, dom]) {
>-  // HTML is needed for EventHandler. Provide a dummy interface for
>-  // LinkStyle which HTML depends on but we're not testing.
>-  idlArray.add_untested_idls('interface LinkStyle {};');
>-  idlArray.add_untested_idls(html);
>   idlArray.add_idls(dom);
>+  idlArray.add_dependency_idls(html);
>   idlArray.add_objects({
>     EventTarget: ['new EventTarget()'],
>     Event: ['document.createEvent("Event")', 'new Event("foo")'],
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/encoding/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/encoding/idlharness-expected.txt
>index ecad4499bac3f1b22d151749411747566cf56656..f3e5f15f3834987c108482184a02f3d57d82daed 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/encoding/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/encoding/idlharness-expected.txt
>@@ -11,13 +11,9 @@ PASS TextDecoder interface: existence and properties of interface prototype obje
> PASS TextDecoder interface: existence and properties of interface prototype object's "constructor" property 
> PASS TextDecoder interface: existence and properties of interface prototype object's @@unscopables property 
> PASS TextDecoder interface: attribute encoding 
>-PASS Unscopable handled correctly for encoding property on TextDecoder 
> PASS TextDecoder interface: attribute fatal 
>-PASS Unscopable handled correctly for fatal property on TextDecoder 
> PASS TextDecoder interface: attribute ignoreBOM 
>-PASS Unscopable handled correctly for ignoreBOM property on TextDecoder 
> PASS TextDecoder interface: operation decode(BufferSource, TextDecodeOptions) 
>-PASS Unscopable handled correctly for decode(BufferSource, TextDecodeOptions) on TextDecoder 
> PASS TextDecoder must be primary interface of new TextDecoder() 
> PASS Stringification of new TextDecoder() 
> PASS TextDecoder interface: new TextDecoder() must inherit property "encoding" with the proper type 
>@@ -32,9 +28,7 @@ PASS TextEncoder interface: existence and properties of interface prototype obje
> PASS TextEncoder interface: existence and properties of interface prototype object's "constructor" property 
> PASS TextEncoder interface: existence and properties of interface prototype object's @@unscopables property 
> PASS TextEncoder interface: attribute encoding 
>-PASS Unscopable handled correctly for encoding property on TextEncoder 
> PASS TextEncoder interface: operation encode(USVString) 
>-PASS Unscopable handled correctly for encode(USVString) on TextEncoder 
> PASS TextEncoder must be primary interface of new TextEncoder() 
> PASS Stringification of new TextEncoder() 
> PASS TextEncoder interface: new TextEncoder() must inherit property "encoding" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/eventsource/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/eventsource/interfaces-expected.txt
>index 350f21f73cd666043f2e402057db4e3a6dc2000d..bad30adff60f3b26037164701a6ad80efa89dfe8 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/eventsource/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/eventsource/interfaces-expected.txt
>@@ -1,4 +1,4 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> Blocked access to external URL http://foo/
> CONSOLE MESSAGE: EventSource cannot load http://foo/ due to access control checks.
> EventSource IDL tests
>@@ -11,17 +11,13 @@ PASS EventTarget interface: existence and properties of interface prototype obje
> PASS EventTarget interface: existence and properties of interface prototype object's "constructor" property 
> PASS EventTarget interface: existence and properties of interface prototype object's @@unscopables property 
> PASS EventTarget interface: operation addEventListener(DOMString, EventListener, [object Object],[object Object]) 
>-PASS Unscopable handled correctly for addEventListener(DOMString, EventListener, [object Object],[object Object]) on EventTarget 
> PASS EventTarget interface: operation removeEventListener(DOMString, EventListener, [object Object],[object Object]) 
>-PASS Unscopable handled correctly for removeEventListener(DOMString, EventListener, [object Object],[object Object]) on EventTarget 
> PASS EventTarget interface: operation dispatchEvent(Event) 
>-PASS Unscopable handled correctly for dispatchEvent(Event) on EventTarget 
> PASS EventListener interface: existence and properties of interface object 
> PASS EventListener interface: existence and properties of interface prototype object 
> PASS EventListener interface: existence and properties of interface prototype object's "constructor" property 
> PASS EventListener interface: existence and properties of interface prototype object's @@unscopables property 
> PASS EventListener interface: operation handleEvent(Event) 
>-PASS Unscopable handled correctly for handleEvent(Event) on EventListener 
> PASS EventSource interface: existence and properties of interface object 
> PASS EventSource interface object length 
> PASS EventSource interface object name 
>@@ -29,9 +25,7 @@ PASS EventSource interface: existence and properties of interface prototype obje
> PASS EventSource interface: existence and properties of interface prototype object's "constructor" property 
> PASS EventSource interface: existence and properties of interface prototype object's @@unscopables property 
> PASS EventSource interface: attribute url 
>-PASS Unscopable handled correctly for url property on EventSource 
> PASS EventSource interface: attribute withCredentials 
>-PASS Unscopable handled correctly for withCredentials property on EventSource 
> PASS EventSource interface: constant CONNECTING on interface object 
> PASS EventSource interface: constant CONNECTING on interface prototype object 
> PASS EventSource interface: constant OPEN on interface object 
>@@ -39,15 +33,10 @@ PASS EventSource interface: constant OPEN on interface prototype object
> PASS EventSource interface: constant CLOSED on interface object 
> PASS EventSource interface: constant CLOSED on interface prototype object 
> PASS EventSource interface: attribute readyState 
>-PASS Unscopable handled correctly for readyState property on EventSource 
> PASS EventSource interface: attribute onopen 
>-PASS Unscopable handled correctly for onopen property on EventSource 
> PASS EventSource interface: attribute onmessage 
>-PASS Unscopable handled correctly for onmessage property on EventSource 
> PASS EventSource interface: attribute onerror 
>-PASS Unscopable handled correctly for onerror property on EventSource 
> PASS EventSource interface: operation close() 
>-PASS Unscopable handled correctly for close() on EventSource 
> PASS EventSource must be primary interface of new EventSource("http://foo") 
> PASS Stringification of new EventSource("http://foo") 
> PASS EventSource interface: new EventSource("http://foo") must inherit property "url" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/headers/headers-idl-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/headers/headers-idl-expected.txt
>index a3f80f7c4fe4e5b0177486d6a1e7f3de7540fad4..71976aff731ab55d2bba48695837852ed16253f7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/headers/headers-idl-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/headers/headers-idl-expected.txt
>@@ -6,25 +6,16 @@ PASS Headers interface: existence and properties of interface prototype object
> PASS Headers interface: existence and properties of interface prototype object's "constructor" property 
> PASS Headers interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Headers interface: operation append(ByteString, ByteString) 
>-PASS Unscopable handled correctly for append(ByteString, ByteString) on Headers 
> PASS Headers interface: operation delete(ByteString) 
>-PASS Unscopable handled correctly for delete(ByteString) on Headers 
> PASS Headers interface: operation get(ByteString) 
>-PASS Unscopable handled correctly for get(ByteString) on Headers 
> PASS Headers interface: operation has(ByteString) 
>-PASS Unscopable handled correctly for has(ByteString) on Headers 
> PASS Headers interface: operation set(ByteString, ByteString) 
>-PASS Unscopable handled correctly for set(ByteString, ByteString) on Headers 
> PASS Testing Symbol.iterator property of iterable interface Headers 
> PASS Testing pair iterable interface Headers 
> PASS Headers interface: operation entries() 
>-PASS Unscopable handled correctly for entries() on Headers 
> PASS Headers interface: operation keys() 
>-PASS Unscopable handled correctly for keys() on Headers 
> PASS Headers interface: operation values() 
>-PASS Unscopable handled correctly for values() on Headers 
> PASS Headers interface: operation forEach(function, any) 
>-PASS Unscopable handled correctly for forEach(function, any) on Headers 
> PASS Headers must be primary interface of new Headers() 
> PASS Stringification of new Headers() 
> PASS Headers interface: new Headers() must inherit property "append(ByteString, ByteString)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/request/request-idl-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/request/request-idl-expected.txt
>index fc66125e3c8012b262ccdfc13d1b0a81706f75d6..60a779c9ee49832c401ce3086b625bc7aa998943 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/request/request-idl-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/request/request-idl-expected.txt
>@@ -6,43 +6,24 @@ PASS Request interface: existence and properties of interface prototype object
> PASS Request interface: existence and properties of interface prototype object's "constructor" property 
> PASS Request interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Request interface: attribute method 
>-PASS Unscopable handled correctly for method property on Request 
> PASS Request interface: attribute url 
>-PASS Unscopable handled correctly for url property on Request 
> PASS Request interface: attribute headers 
>-PASS Unscopable handled correctly for headers property on Request 
> PASS Request interface: attribute destination 
>-PASS Unscopable handled correctly for destination property on Request 
> PASS Request interface: attribute referrer 
>-PASS Unscopable handled correctly for referrer property on Request 
> PASS Request interface: attribute referrerPolicy 
>-PASS Unscopable handled correctly for referrerPolicy property on Request 
> PASS Request interface: attribute mode 
>-PASS Unscopable handled correctly for mode property on Request 
> PASS Request interface: attribute credentials 
>-PASS Unscopable handled correctly for credentials property on Request 
> PASS Request interface: attribute cache 
>-PASS Unscopable handled correctly for cache property on Request 
> PASS Request interface: attribute redirect 
>-PASS Unscopable handled correctly for redirect property on Request 
> PASS Request interface: attribute integrity 
>-PASS Unscopable handled correctly for integrity property on Request 
> PASS Request interface: operation clone() 
>-PASS Unscopable handled correctly for clone() on Request 
> PASS Request interface: attribute body 
>-PASS Unscopable handled correctly for body property on Request 
> PASS Request interface: attribute bodyUsed 
>-PASS Unscopable handled correctly for bodyUsed property on Request 
> PASS Request interface: operation arrayBuffer() 
>-PASS Unscopable handled correctly for arrayBuffer() on Request 
> PASS Request interface: operation blob() 
>-PASS Unscopable handled correctly for blob() on Request 
> PASS Request interface: operation formData() 
>-PASS Unscopable handled correctly for formData() on Request 
> PASS Request interface: operation json() 
>-PASS Unscopable handled correctly for json() on Request 
> PASS Request interface: operation text() 
>-PASS Unscopable handled correctly for text() on Request 
> PASS Request must be primary interface of new Request("") 
> PASS Stringification of new Request("") 
> PASS Request interface: new Request("") must inherit property "method" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/response/response-idl-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/response/response-idl-expected.txt
>index 263ccaa76e67fa18591d247640cb1019b4e1878b..4afab0229e4e982577cf276758a3a9c91dfabead 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/fetch/api/response/response-idl-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/fetch/api/response/response-idl-expected.txt
>@@ -6,39 +6,22 @@ PASS Response interface: existence and properties of interface prototype object
> PASS Response interface: existence and properties of interface prototype object's "constructor" property 
> PASS Response interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Response interface: operation error() 
>-PASS Unscopable handled correctly for error() on Response 
> PASS Response interface: operation redirect(USVString, unsigned short) 
>-PASS Unscopable handled correctly for redirect(USVString, unsigned short) on Response 
> PASS Response interface: attribute type 
>-PASS Unscopable handled correctly for type property on Response 
> PASS Response interface: attribute url 
>-PASS Unscopable handled correctly for url property on Response 
> PASS Response interface: attribute status 
>-PASS Unscopable handled correctly for status property on Response 
> PASS Response interface: attribute ok 
>-PASS Unscopable handled correctly for ok property on Response 
> PASS Response interface: attribute statusText 
>-PASS Unscopable handled correctly for statusText property on Response 
> PASS Response interface: attribute headers 
>-PASS Unscopable handled correctly for headers property on Response 
> FAIL Response interface: attribute trailer assert_true: The prototype object must have a property "trailer" expected true got false
>-PASS Unscopable handled correctly for trailer property on Response 
> PASS Response interface: operation clone() 
>-PASS Unscopable handled correctly for clone() on Response 
> PASS Response interface: attribute body 
>-PASS Unscopable handled correctly for body property on Response 
> PASS Response interface: attribute bodyUsed 
>-PASS Unscopable handled correctly for bodyUsed property on Response 
> PASS Response interface: operation arrayBuffer() 
>-PASS Unscopable handled correctly for arrayBuffer() on Response 
> PASS Response interface: operation blob() 
>-PASS Unscopable handled correctly for blob() on Response 
> PASS Response interface: operation formData() 
>-PASS Unscopable handled correctly for formData() on Response 
> PASS Response interface: operation json() 
>-PASS Unscopable handled correctly for json() on Response 
> PASS Response interface: operation text() 
>-PASS Unscopable handled correctly for text() on Response 
> PASS Response must be primary interface of new Response() 
> PASS Stringification of new Response() 
> PASS Response interface: new Response() must inherit property "error()" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/hr-time/idlharness.html b/LayoutTests/imported/w3c/web-platform-tests/hr-time/idlharness.html
>index 4abaf6033fd437c2691b8f540ec6499484acc6e0..ba36a0fb2cee80dd61c9e6dfb09be40873100bfd 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/hr-time/idlharness.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/hr-time/idlharness.html
>@@ -16,10 +16,11 @@
> <script>
> 'use strict';
> 
>-function doTest([html, hr_time]) {
>+function doTest([dom, html, hr_time]) {
>   var idl_array = new IdlArray();
>-  idl_array.add_untested_idls(html, { only: ['WindowOrWorkerGlobalScope'] });
>   idl_array.add_idls(hr_time);
>+  idl_array.add_dependency_idls(dom);
>+  idl_array.add_dependency_idls(html);
>   idl_array.add_objects({
>     Performance: ["window.performance"],
>     Window: ["window"],
>@@ -32,7 +33,8 @@ function fetchText(url) {
> }
> 
> promise_test(() => {
>-  return Promise.all(['/interfaces/html.idl',
>+  return Promise.all(['/interfaces/dom.idl',
>+                      '/interfaces/html.idl',
>                       '/interfaces/hr-time.idl'].map(fetchText))
>                 .then(doTest);
> }, 'Test driver');
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/html/webappapis/animation-frames/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/html/webappapis/animation-frames/idlharness-expected.txt
>index 41990aa931b1ec9e5c98d67153d344b9697837d7..6d8bf6e7f71f159939f33632c1fae9dd763194fd 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/html/webappapis/animation-frames/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/html/webappapis/animation-frames/idlharness-expected.txt
>@@ -1,4 +1,4 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> idlharness test
> 
> This test validates the WebIDL included in the Timing control for script-based animations specification.
>@@ -10,10 +10,9 @@ partial interface Window {
> 
> callback FrameRequestCallback = void (DOMHighResTimeStamp time);
> 
>+PASS Partial interface Window: original interface defined 
> PASS Window interface: operation requestAnimationFrame(FrameRequestCallback) 
>-PASS Unscopable handled correctly for requestAnimationFrame(FrameRequestCallback) on Window 
> PASS Window interface: operation cancelAnimationFrame(long) 
>-PASS Unscopable handled correctly for cancelAnimationFrame(long) on Window 
> PASS Window interface: window must inherit property "requestAnimationFrame(FrameRequestCallback)" with the proper type 
> PASS Window interface: calling requestAnimationFrame(FrameRequestCallback) on window with too few arguments must throw TypeError 
> PASS Window interface: window must inherit property "cancelAnimationFrame(long)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/interfaces/IndexedDB.idl b/LayoutTests/imported/w3c/web-platform-tests/interfaces/IndexedDB.idl
>index 89924c09b49e5c5a7a7fcf188eb4c224c3ba032a..cc41a23ba0cd0fca3cf0602eb167be4f1465a7ca 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/interfaces/IndexedDB.idl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/interfaces/IndexedDB.idl
>@@ -150,7 +150,7 @@ interface IDBKeyRange {
>                            optional boolean lowerOpen = false,
>                            optional boolean upperOpen = false);
> 
>-  boolean includes(any key);
>+  boolean _includes(any key);
> };
> 
> [Exposed=(Window,Worker)]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/interfaces/intersection-observer.idl b/LayoutTests/imported/w3c/web-platform-tests/interfaces/intersection-observer.idl
>new file mode 100644
>index 0000000000000000000000000000000000000000..b48e1cbab37fef9b9c8dd5efb03fc6c222a3e856
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/interfaces/intersection-observer.idl
>@@ -0,0 +1,45 @@
>+// GENERATED CONTENT - DO NOT EDIT
>+// Content was automatically extracted by Reffy into reffy-reports
>+// (https://github.com/tidoust/reffy-reports)
>+// Source: Intersection Observer (https://w3c.github.io/IntersectionObserver/)
>+
>+callback IntersectionObserverCallback = void (sequence<IntersectionObserverEntry> entries, IntersectionObserver observer);
>+
>+[Constructor(IntersectionObserverCallback callback, optional IntersectionObserverInit options),
>+ Exposed=Window]
>+interface IntersectionObserver {
>+  readonly attribute Element? root;
>+  readonly attribute DOMString rootMargin;
>+  readonly attribute FrozenArray<double> thresholds;
>+  void observe(Element target);
>+  void unobserve(Element target);
>+  void disconnect();
>+  sequence<IntersectionObserverEntry> takeRecords();
>+};
>+
>+[Constructor(IntersectionObserverEntryInit intersectionObserverEntryInit)]
>+interface IntersectionObserverEntry {
>+  readonly attribute DOMHighResTimeStamp time;
>+  readonly attribute DOMRectReadOnly rootBounds;
>+  readonly attribute DOMRectReadOnly boundingClientRect;
>+  readonly attribute DOMRectReadOnly intersectionRect;
>+  readonly attribute boolean isIntersecting;
>+  readonly attribute double intersectionRatio;
>+  readonly attribute Element target;
>+};
>+
>+dictionary IntersectionObserverEntryInit {
>+  required DOMHighResTimeStamp time;
>+  required DOMRectInit rootBounds;
>+  required DOMRectInit boundingClientRect;
>+  required DOMRectInit intersectionRect;
>+  required boolean isIntersecting;
>+  required double intersectionRatio;
>+  required Element target;
>+};
>+
>+dictionary IntersectionObserverInit {
>+  Element?  root = null;
>+  DOMString rootMargin = "0px";
>+  (double or sequence<double>) threshold = 0;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/media-source/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/media-source/interfaces-expected.txt
>index d0a2d1a821abbecbbb905c0481926750835ca6b4..967f1bc229b896b19dc53a95ecd7b55f2916f153 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/media-source/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/media-source/interfaces-expected.txt
>@@ -1,4 +1,9 @@
> 
>+PASS Partial interface URL: original interface defined 
>+PASS Partial interface URL: valid exposure set 
>+PASS Partial interface AudioTrack: original interface defined 
>+PASS Partial interface VideoTrack: original interface defined 
>+PASS Partial interface TextTrack: original interface defined 
> PASS URL interface: operation createObjectURL(MediaSource) 
> PASS AudioTrack interface: attribute sourceBuffer 
> PASS VideoTrack interface: attribute sourceBuffer 
>@@ -8,6 +13,7 @@ PASS MediaSource interface object length
> PASS MediaSource interface object name 
> PASS MediaSource interface: existence and properties of interface prototype object 
> PASS MediaSource interface: existence and properties of interface prototype object's "constructor" property 
>+PASS MediaSource interface: existence and properties of interface prototype object's @@unscopables property 
> PASS MediaSource interface: attribute sourceBuffers 
> PASS MediaSource interface: attribute activeSourceBuffers 
> PASS MediaSource interface: attribute readyState 
>@@ -18,40 +24,35 @@ PASS MediaSource interface: attribute onsourceclose
> PASS MediaSource interface: operation addSourceBuffer(DOMString) 
> PASS MediaSource interface: operation removeSourceBuffer(SourceBuffer) 
> PASS MediaSource interface: operation endOfStream(EndOfStreamError) 
>-PASS MediaSource interface: operation setLiveSeekableRange(double,double) 
>+PASS MediaSource interface: operation setLiveSeekableRange(double, double) 
> PASS MediaSource interface: operation clearLiveSeekableRange() 
> PASS MediaSource interface: operation isTypeSupported(DOMString) 
> PASS MediaSource must be primary interface of mediaSource 
> PASS Stringification of mediaSource 
>-PASS MediaSource interface: mediaSource must inherit property "sourceBuffers" with the proper type (0) 
>-PASS MediaSource interface: mediaSource must inherit property "activeSourceBuffers" with the proper type (1) 
>-PASS MediaSource interface: mediaSource must inherit property "readyState" with the proper type (2) 
>-PASS MediaSource interface: mediaSource must inherit property "duration" with the proper type (3) 
>-PASS MediaSource interface: mediaSource must inherit property "onsourceopen" with the proper type (4) 
>-PASS MediaSource interface: mediaSource must inherit property "onsourceended" with the proper type (5) 
>-PASS MediaSource interface: mediaSource must inherit property "onsourceclose" with the proper type (6) 
>-PASS MediaSource interface: mediaSource must inherit property "addSourceBuffer" with the proper type (7) 
>+PASS MediaSource interface: mediaSource must inherit property "sourceBuffers" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "activeSourceBuffers" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "readyState" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "duration" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "onsourceopen" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "onsourceended" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "onsourceclose" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "addSourceBuffer(DOMString)" with the proper type 
> PASS MediaSource interface: calling addSourceBuffer(DOMString) on mediaSource with too few arguments must throw TypeError 
>-PASS MediaSource interface: mediaSource must inherit property "removeSourceBuffer" with the proper type (8) 
>+PASS MediaSource interface: mediaSource must inherit property "removeSourceBuffer(SourceBuffer)" with the proper type 
> PASS MediaSource interface: calling removeSourceBuffer(SourceBuffer) on mediaSource with too few arguments must throw TypeError 
>-PASS MediaSource interface: mediaSource must inherit property "endOfStream" with the proper type (9) 
>+PASS MediaSource interface: mediaSource must inherit property "endOfStream(EndOfStreamError)" with the proper type 
> PASS MediaSource interface: calling endOfStream(EndOfStreamError) on mediaSource with too few arguments must throw TypeError 
>-PASS MediaSource interface: mediaSource must inherit property "setLiveSeekableRange" with the proper type (10) 
>-PASS MediaSource interface: calling setLiveSeekableRange(double,double) on mediaSource with too few arguments must throw TypeError 
>-PASS MediaSource interface: mediaSource must inherit property "clearLiveSeekableRange" with the proper type (11) 
>-PASS MediaSource interface: mediaSource must inherit property "isTypeSupported" with the proper type (12) 
>+PASS MediaSource interface: mediaSource must inherit property "setLiveSeekableRange(double, double)" with the proper type 
>+PASS MediaSource interface: calling setLiveSeekableRange(double, double) on mediaSource with too few arguments must throw TypeError 
>+PASS MediaSource interface: mediaSource must inherit property "clearLiveSeekableRange()" with the proper type 
>+PASS MediaSource interface: mediaSource must inherit property "isTypeSupported(DOMString)" with the proper type 
> PASS MediaSource interface: calling isTypeSupported(DOMString) on mediaSource with too few arguments must throw TypeError 
>-PASS EventTarget interface: mediaSource must inherit property "addEventListener" with the proper type (0) 
>-PASS EventTarget interface: calling addEventListener(DOMString,EventListener,boolean) on mediaSource with too few arguments must throw TypeError 
>-PASS EventTarget interface: mediaSource must inherit property "removeEventListener" with the proper type (1) 
>-PASS EventTarget interface: calling removeEventListener(DOMString,EventListener,boolean) on mediaSource with too few arguments must throw TypeError 
>-PASS EventTarget interface: mediaSource must inherit property "dispatchEvent" with the proper type (2) 
>-PASS EventTarget interface: calling dispatchEvent(Event) on mediaSource with too few arguments must throw TypeError 
> PASS SourceBuffer interface: existence and properties of interface object 
> PASS SourceBuffer interface object length 
> PASS SourceBuffer interface object name 
> PASS SourceBuffer interface: existence and properties of interface prototype object 
> PASS SourceBuffer interface: existence and properties of interface prototype object's "constructor" property 
>+PASS SourceBuffer interface: existence and properties of interface prototype object's @@unscopables property 
> PASS SourceBuffer interface: attribute mode 
> PASS SourceBuffer interface: attribute updating 
> PASS SourceBuffer interface: attribute buffered 
>@@ -68,51 +69,40 @@ PASS SourceBuffer interface: attribute onerror
> PASS SourceBuffer interface: attribute onabort 
> PASS SourceBuffer interface: operation appendBuffer(BufferSource) 
> PASS SourceBuffer interface: operation abort() 
>-PASS SourceBuffer interface: operation remove(double,unrestricted double) 
>+PASS SourceBuffer interface: operation remove(double, unrestricted double) 
> PASS SourceBuffer must be primary interface of sourceBuffer 
> PASS Stringification of sourceBuffer 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "mode" with the proper type (0) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "updating" with the proper type (1) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "buffered" with the proper type (2) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "timestampOffset" with the proper type (3) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "audioTracks" with the proper type (4) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "videoTracks" with the proper type (5) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "textTracks" with the proper type (6) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "appendWindowStart" with the proper type (7) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "appendWindowEnd" with the proper type (8) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "onupdatestart" with the proper type (9) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "onupdate" with the proper type (10) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "onupdateend" with the proper type (11) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "onerror" with the proper type (12) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "onabort" with the proper type (13) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "appendBuffer" with the proper type (14) 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "mode" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "updating" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "buffered" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "timestampOffset" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "audioTracks" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "videoTracks" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "textTracks" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "appendWindowStart" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "appendWindowEnd" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "onupdatestart" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "onupdate" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "onupdateend" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "onerror" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "onabort" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "appendBuffer(BufferSource)" with the proper type 
> PASS SourceBuffer interface: calling appendBuffer(BufferSource) on sourceBuffer with too few arguments must throw TypeError 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "abort" with the proper type (15) 
>-PASS SourceBuffer interface: sourceBuffer must inherit property "remove" with the proper type (16) 
>-PASS SourceBuffer interface: calling remove(double,unrestricted double) on sourceBuffer with too few arguments must throw TypeError 
>-PASS EventTarget interface: sourceBuffer must inherit property "addEventListener" with the proper type (0) 
>-PASS EventTarget interface: calling addEventListener(DOMString,EventListener,boolean) on sourceBuffer with too few arguments must throw TypeError 
>-PASS EventTarget interface: sourceBuffer must inherit property "removeEventListener" with the proper type (1) 
>-PASS EventTarget interface: calling removeEventListener(DOMString,EventListener,boolean) on sourceBuffer with too few arguments must throw TypeError 
>-PASS EventTarget interface: sourceBuffer must inherit property "dispatchEvent" with the proper type (2) 
>-PASS EventTarget interface: calling dispatchEvent(Event) on sourceBuffer with too few arguments must throw TypeError 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "abort()" with the proper type 
>+PASS SourceBuffer interface: sourceBuffer must inherit property "remove(double, unrestricted double)" with the proper type 
>+PASS SourceBuffer interface: calling remove(double, unrestricted double) on sourceBuffer with too few arguments must throw TypeError 
> PASS SourceBufferList interface: existence and properties of interface object 
> PASS SourceBufferList interface object length 
> PASS SourceBufferList interface object name 
> PASS SourceBufferList interface: existence and properties of interface prototype object 
> PASS SourceBufferList interface: existence and properties of interface prototype object's "constructor" property 
>+PASS SourceBufferList interface: existence and properties of interface prototype object's @@unscopables property 
> PASS SourceBufferList interface: attribute length 
> PASS SourceBufferList interface: attribute onaddsourcebuffer 
> PASS SourceBufferList interface: attribute onremovesourcebuffer 
> PASS SourceBufferList must be primary interface of mediaSource.sourceBuffers 
> PASS Stringification of mediaSource.sourceBuffers 
>-PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "length" with the proper type (0) 
>-PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "onaddsourcebuffer" with the proper type (1) 
>-PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "onremovesourcebuffer" with the proper type (2) 
>-PASS EventTarget interface: mediaSource.sourceBuffers must inherit property "addEventListener" with the proper type (0) 
>-PASS EventTarget interface: calling addEventListener(DOMString,EventListener,boolean) on mediaSource.sourceBuffers with too few arguments must throw TypeError 
>-PASS EventTarget interface: mediaSource.sourceBuffers must inherit property "removeEventListener" with the proper type (1) 
>-PASS EventTarget interface: calling removeEventListener(DOMString,EventListener,boolean) on mediaSource.sourceBuffers with too few arguments must throw TypeError 
>-PASS EventTarget interface: mediaSource.sourceBuffers must inherit property "dispatchEvent" with the proper type (2) 
>-PASS EventTarget interface: calling dispatchEvent(Event) on mediaSource.sourceBuffers with too few arguments must throw TypeError 
>+PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "length" with the proper type 
>+PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "onaddsourcebuffer" with the proper type 
>+PASS SourceBufferList interface: mediaSource.sourceBuffers must inherit property "onremovesourcebuffer" with the proper type 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/notifications/interfaces-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/notifications/interfaces-expected.txt
>index 22b44fdba456caaa826d371ddbaec70daf668b37..97066b2b64b324c31a82aca385941043c9feef47 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/notifications/interfaces-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/notifications/interfaces-expected.txt
>@@ -1,5 +1,5 @@
>-CONSOLE MESSAGE: line 331: callback not yet supported
>-CONSOLE MESSAGE: line 331: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
>+CONSOLE MESSAGE: line 482: callback not yet supported
> 
> PASS Notification interface: existence and properties of interface object 
> PASS Notification interface object length 
>@@ -8,51 +8,28 @@ PASS Notification interface: existence and properties of interface prototype obj
> PASS Notification interface: existence and properties of interface prototype object's "constructor" property 
> PASS Notification interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Notification interface: attribute permission 
>-PASS Unscopable handled correctly for permission property on Notification 
> PASS Notification interface: operation requestPermission(NotificationPermissionCallback) 
>-PASS Unscopable handled correctly for requestPermission(NotificationPermissionCallback) on Notification 
> FAIL Notification interface: attribute maxActions assert_own_property: The interface object must have a property "maxActions" expected property "maxActions" missing
>-PASS Unscopable handled correctly for maxActions property on Notification 
> PASS Notification interface: attribute onclick 
>-PASS Unscopable handled correctly for onclick property on Notification 
> PASS Notification interface: attribute onshow 
>-PASS Unscopable handled correctly for onshow property on Notification 
> PASS Notification interface: attribute onerror 
>-PASS Unscopable handled correctly for onerror property on Notification 
> PASS Notification interface: attribute onclose 
>-PASS Unscopable handled correctly for onclose property on Notification 
> PASS Notification interface: attribute title 
>-PASS Unscopable handled correctly for title property on Notification 
> PASS Notification interface: attribute dir 
>-PASS Unscopable handled correctly for dir property on Notification 
> PASS Notification interface: attribute lang 
>-PASS Unscopable handled correctly for lang property on Notification 
> PASS Notification interface: attribute body 
>-PASS Unscopable handled correctly for body property on Notification 
> PASS Notification interface: attribute tag 
>-PASS Unscopable handled correctly for tag property on Notification 
> FAIL Notification interface: attribute image assert_true: The prototype object must have a property "image" expected true got false
>-PASS Unscopable handled correctly for image property on Notification 
> PASS Notification interface: attribute icon 
>-PASS Unscopable handled correctly for icon property on Notification 
> FAIL Notification interface: attribute badge assert_true: The prototype object must have a property "badge" expected true got false
>-PASS Unscopable handled correctly for badge property on Notification 
> FAIL Notification interface: attribute vibrate assert_true: The prototype object must have a property "vibrate" expected true got false
>-PASS Unscopable handled correctly for vibrate property on Notification 
> FAIL Notification interface: attribute timestamp assert_true: The prototype object must have a property "timestamp" expected true got false
>-PASS Unscopable handled correctly for timestamp property on Notification 
> FAIL Notification interface: attribute renotify assert_true: The prototype object must have a property "renotify" expected true got false
>-PASS Unscopable handled correctly for renotify property on Notification 
> FAIL Notification interface: attribute silent assert_true: The prototype object must have a property "silent" expected true got false
>-PASS Unscopable handled correctly for silent property on Notification 
> FAIL Notification interface: attribute requireInteraction assert_true: The prototype object must have a property "requireInteraction" expected true got false
>-PASS Unscopable handled correctly for requireInteraction property on Notification 
> FAIL Notification interface: attribute data assert_true: The prototype object must have a property "data" expected true got false
>-PASS Unscopable handled correctly for data property on Notification 
> FAIL Notification interface: attribute actions assert_true: The prototype object must have a property "actions" expected true got false
>-PASS Unscopable handled correctly for actions property on Notification 
> PASS Notification interface: operation close() 
>-PASS Unscopable handled correctly for close() on Notification 
> PASS Notification must be primary interface of new Notification("Running idlharness.") 
> PASS Stringification of new Notification("Running idlharness.") 
> PASS Notification interface: new Notification("Running idlharness.") must inherit property "permission" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resource-timing/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/resource-timing/idlharness-expected.txt
>index c02c3d60007c1698c67bfd6d4adc627018b5cdb3..c12042c2547213ae2d8889a71785b89a3d2b02a7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resource-timing/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resource-timing/idlharness-expected.txt
>@@ -1,12 +1,10 @@
> Resource Timing IDL tests
> 
> 
>+PASS Partial interface Performance: original interface defined 
> PASS Performance interface: operation clearResourceTimings() 
>-PASS Unscopable handled correctly for clearResourceTimings() on Performance 
> PASS Performance interface: operation setResourceTimingBufferSize(unsigned long) 
>-PASS Unscopable handled correctly for setResourceTimingBufferSize(unsigned long) on Performance 
> PASS Performance interface: attribute onresourcetimingbufferfull 
>-PASS Unscopable handled correctly for onresourcetimingbufferfull property on Performance 
> PASS Performance interface: window.performance must inherit property "clearResourceTimings()" with the proper type 
> PASS Performance interface: window.performance must inherit property "setResourceTimingBufferSize(unsigned long)" with the proper type 
> PASS Performance interface: calling setResourceTimingBufferSize(unsigned long) on window.performance with too few arguments must throw TypeError 
>@@ -18,41 +16,23 @@ PASS PerformanceResourceTiming interface: existence and properties of interface
> PASS PerformanceResourceTiming interface: existence and properties of interface prototype object's "constructor" property 
> PASS PerformanceResourceTiming interface: existence and properties of interface prototype object's @@unscopables property 
> PASS PerformanceResourceTiming interface: attribute initiatorType 
>-PASS Unscopable handled correctly for initiatorType property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute nextHopProtocol 
>-PASS Unscopable handled correctly for nextHopProtocol property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute workerStart 
>-PASS Unscopable handled correctly for workerStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute redirectStart 
>-PASS Unscopable handled correctly for redirectStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute redirectEnd 
>-PASS Unscopable handled correctly for redirectEnd property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute fetchStart 
>-PASS Unscopable handled correctly for fetchStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute domainLookupStart 
>-PASS Unscopable handled correctly for domainLookupStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute domainLookupEnd 
>-PASS Unscopable handled correctly for domainLookupEnd property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute connectStart 
>-PASS Unscopable handled correctly for connectStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute connectEnd 
>-PASS Unscopable handled correctly for connectEnd property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute secureConnectionStart 
>-PASS Unscopable handled correctly for secureConnectionStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute requestStart 
>-PASS Unscopable handled correctly for requestStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute responseStart 
>-PASS Unscopable handled correctly for responseStart property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: attribute responseEnd 
>-PASS Unscopable handled correctly for responseEnd property on PerformanceResourceTiming 
> FAIL PerformanceResourceTiming interface: attribute transferSize assert_true: The prototype object must have a property "transferSize" expected true got false
>-PASS Unscopable handled correctly for transferSize property on PerformanceResourceTiming 
> FAIL PerformanceResourceTiming interface: attribute encodedBodySize assert_true: The prototype object must have a property "encodedBodySize" expected true got false
>-PASS Unscopable handled correctly for encodedBodySize property on PerformanceResourceTiming 
> FAIL PerformanceResourceTiming interface: attribute decodedBodySize assert_true: The prototype object must have a property "decodedBodySize" expected true got false
>-PASS Unscopable handled correctly for decodedBodySize property on PerformanceResourceTiming 
> PASS PerformanceResourceTiming interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on PerformanceResourceTiming 
> PASS PerformanceResourceTiming must be primary interface of window.performance.getEntriesByType('resource')[0] 
> PASS Stringification of window.performance.getEntriesByType('resource')[0] 
> PASS PerformanceResourceTiming interface: window.performance.getEntriesByType('resource')[0] must inherit property "initiatorType" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/idlharness.js b/LayoutTests/imported/w3c/web-platform-tests/resources/idlharness.js
>index c3045c49f909c9514597a6d6f8a9a3f7fe0f4df2..a088bc4c2a78002500fb879410e1800f16845af7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/idlharness.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/idlharness.js
>@@ -48,6 +48,13 @@ policies and contribution forms [3].
>  */
> (function(){
> "use strict";
>+// Support subsetTestByKey from /common/subset-tests-by-key.js, but make it optional
>+if (!('subsetTestByKey' in self)) {
>+    self.subsetTestByKey = function(key, callback, ...args) {
>+      return callback(...args);
>+    }
>+    self.shouldRunSubTest = () => true;
>+}
> /// Helpers ///
> function constValue (cnt)
> //@{
>@@ -63,6 +70,11 @@ function constValue (cnt)
> function minOverloadLength(overloads)
> //@{
> {
>+    // "The value of the Function objectâs âlengthâ property is
>+    // a Number determined as follows:
>+    // ". . .
>+    // "Return the length of the shortest argument list of the
>+    // entries in S."
>     if (!overloads.length) {
>         return 0;
>     }
>@@ -183,11 +195,19 @@ self.IdlArray = function()
>      *   A implements C;
>      *   D implements E;
>      *
>-     * results in { A: ["B", "C"], D: ["E"] }.
>+     * results in this["implements"] = { A: ["B", "C"], D: ["E"] }.
>+     *
>+     * Similarly,
>+     *
>+     *   interface A : B {};
>+     *   interface B : C {};
>+     *
>+     * results in this["inheritance"] = { A: "B", B: "C" }
>      */
>     this.partials = [];
>     this["implements"] = {};
>     this["includes"] = {};
>+    this["inheritance"] = {};
> };
> 
> //@}
>@@ -204,19 +224,142 @@ IdlArray.prototype.add_untested_idls = function(raw_idls, options)
> {
>     /** Entry point.  See documentation at beginning of file. */
>     var parsed_idls = WebIDL2.parse(raw_idls);
>-    for (var i = 0; i < parsed_idls.length; i++)
>-    {
>+    this.mark_as_untested(parsed_idls);
>+    this.internal_add_idls(parsed_idls, options);
>+};
>+
>+//@}
>+IdlArray.prototype.mark_as_untested = function (parsed_idls)
>+//@{
>+{
>+    for (var i = 0; i < parsed_idls.length; i++) {
>         parsed_idls[i].untested = true;
>-        if ("members" in parsed_idls[i])
>-        {
>-            for (var j = 0; j < parsed_idls[i].members.length; j++)
>-            {
>+        if ("members" in parsed_idls[i]) {
>+            for (var j = 0; j < parsed_idls[i].members.length; j++) {
>                 parsed_idls[i].members[j].untested = true;
>             }
>         }
>     }
>-    this.internal_add_idls(parsed_idls, options);
> };
>+//@}
>+
>+//@}
>+IdlArray.prototype.is_excluded_by_options = function (name, options)
>+//@{
>+{
>+    return options &&
>+        (options.except && options.except.includes(name)
>+         || options.only && !options.only.includes(name));
>+};
>+//@}
>+
>+//@}
>+IdlArray.prototype.add_dependency_idls = function(raw_idls, options)
>+//@{
>+{
>+    const parsed_idls = WebIDL2.parse(raw_idls);
>+    const new_options = { only: [] }
>+
>+    const all_deps = new Set();
>+    Object.values(this.inheritance).forEach(v => all_deps.add(v));
>+    Object.entries(this.implements).forEach(([k, v]) => {
>+        all_deps.add(k);
>+        all_deps.add(v);
>+    });
>+    // NOTE: If 'A includes B' for B that we care about, then A is also a dep.
>+    Object.keys(this.includes).forEach(k => {
>+        all_deps.add(k);
>+        this.includes[k].forEach(v => all_deps.add(v));
>+    });
>+    this.partials.map(p => p.name).forEach(v => all_deps.add(v));
>+    // Add the attribute idlTypes of all the nested members of all tested idls.
>+    for (const obj of [this.members, this.partials]) {
>+        const tested = Object.values(obj).filter(m => !m.untested && m.members);
>+        for (const parsed of tested) {
>+            for (const attr of Object.values(parsed.members).filter(m => !m.untested && m.type === 'attribute')) {
>+                all_deps.add(attr.idlType.idlType);
>+            }
>+        }
>+    }
>+
>+    if (options && options.except && options.only) {
>+        throw new IdlHarnessError("The only and except options can't be used together.");
>+    }
>+
>+    const should_skip = name => {
>+        // NOTE: Deps are untested, so we're lenient, and skip re-encountered definitions.
>+        // e.g. for 'idl' containing A:B, B:C, C:D
>+        //      array.add_idls(idl, {only: ['A','B']}).
>+        //      array.add_dependency_idls(idl);
>+        // B would be encountered as tested, and encountered as a dep, so we ignore.
>+        return name in this.members
>+            || this.is_excluded_by_options(name, options);
>+    }
>+    // Record of skipped items, in case we later determine they are a dependency.
>+    // Maps name -> [parsed_idl, ...]
>+    const skipped = new Map();
>+    const process = function(parsed) {
>+        var deps = [];
>+        if (parsed.name) {
>+            deps.push(parsed.name);
>+        } else if (parsed.type === "implements") {
>+            deps.push(parsed.target);
>+            deps.push(parsed.implements);
>+        } else if (parsed.type === "includes") {
>+            deps.push(parsed.target);
>+            deps.push(parsed.includes);
>+        }
>+
>+        deps = deps.filter(function(name) {
>+            if (!name || should_skip(name) || !all_deps.has(name)) {
>+                // Flag as skipped, if it's not already processed, so we can
>+                // come back to it later if we retrospectively call it a dep.
>+                if (name && !(name in this.members)) {
>+                    skipped.has(name)
>+                        ? skipped.get(name).push(parsed)
>+                        : skipped.set(name, [parsed]);
>+                }
>+                return false;
>+            }
>+            return true;
>+        }.bind(this));
>+
>+        deps.forEach(function(name) {
>+            new_options.only.push(name);
>+
>+            const follow_up = new Set();
>+            for (const dep_type of ["inheritance", "implements", "includes"]) {
>+                if (parsed[dep_type]) {
>+                    const inheriting = parsed[dep_type];
>+                    const inheritor = parsed.name || parsed.target;
>+                    for (const dep of [inheriting, inheritor]) {
>+                        new_options.only.push(dep);
>+                        all_deps.add(dep);
>+                        follow_up.add(dep);
>+                    }
>+                }
>+            }
>+
>+            for (const deferred of follow_up) {
>+                if (skipped.has(deferred)) {
>+                    const next = skipped.get(deferred);
>+                    skipped.delete(deferred);
>+                    next.forEach(process);
>+                }
>+            }
>+        });
>+    }.bind(this);
>+
>+    for (let parsed of parsed_idls) {
>+        process(parsed);
>+    }
>+
>+    this.mark_as_untested(parsed_idls);
>+
>+    if (new_options.only.length) {
>+        this.internal_add_idls(parsed_idls, new_options);
>+    }
>+}
> 
> //@}
> IdlArray.prototype.internal_add_idls = function(parsed_idls, options)
>@@ -242,22 +385,19 @@ IdlArray.prototype.internal_add_idls = function(parsed_idls, options)
>         throw new IdlHarnessError("The only and except options can't be used together.");
>     }
> 
>-    function should_skip(name)
>-    {
>-        if (options && options.only && options.only.indexOf(name) == -1)
>-        {
>-            return true;
>-        }
>-        if (options && options.except && options.except.indexOf(name) != -1)
>-        {
>-            return true;
>-        }
>-        return false;
>+    var should_skip = name => {
>+        return this.is_excluded_by_options(name, options);
>     }
> 
>     parsed_idls.forEach(function(parsed_idl)
>     {
>-        if (parsed_idl.partial && ["interface", "dictionary"].includes(parsed_idl.type))
>+        var partial_types = [
>+            "interface",
>+            "interface mixin",
>+            "dictionary",
>+            "namespace",
>+        ];
>+        if (parsed_idl.partial && partial_types.includes(parsed_idl.type))
>         {
>             if (should_skip(parsed_idl.name))
>             {
>@@ -304,6 +444,17 @@ IdlArray.prototype.internal_add_idls = function(parsed_idls, options)
>         {
>             throw new IdlHarnessError("Duplicate identifier " + parsed_idl.name);
>         }
>+
>+        if (parsed_idl["inheritance"]) {
>+            // NOTE: Clash should be impossible (would require redefinition of parsed_idl.name).
>+            if (parsed_idl.name in this["inheritance"]
>+                && parsed_idl["inheritance"] != this["inheritance"][parsed_idl.name]) {
>+                throw new IdlHarnessError(
>+                    `Inheritance for ${parsed_idl.name} was already defined`);
>+            }
>+            this["inheritance"][parsed_idl.name] = parsed_idl["inheritance"];
>+        }
>+
>         switch(parsed_idl.type)
>         {
>         case "interface":
>@@ -340,6 +491,10 @@ IdlArray.prototype.internal_add_idls = function(parsed_idls, options)
>                 new IdlInterface(parsed_idl, /* is_callback = */ true, /* is_mixin = */ false);
>             break;
> 
>+        case "namespace":
>+            this.members[parsed_idl.name] = new IdlNamespace(parsed_idl);
>+            break;
>+
>         default:
>             throw parsed_idl.name + ": " + parsed_idl.type + " not yet supported";
>         }
>@@ -553,41 +708,48 @@ IdlArray.prototype.is_json_type = function(type)
> };
> 
> function exposure_set(object, default_set) {
>-    var exposed = object.extAttrs.filter(function(a) { return a.name == "Exposed" });
>-    if (exposed.length > 1 || exposed.length < 0) {
>-        throw new IdlHarnessError("Unexpected Exposed extended attributes on " + memberName + ": " + exposed);
>+    var exposed = object.extAttrs && object.extAttrs.filter(a => a.name === "Exposed");
>+    if (exposed && exposed.length > 1) {
>+        throw new IdlHarnessError(
>+            `Multiple 'Exposed' extended attributes on ${object.name}`);
>     }
> 
>-    if (exposed.length === 0) {
>-        return default_set;
>+    let result = default_set || ["Window"];
>+    if (result && !(result instanceof Set)) {
>+        result = new Set(result);
>     }
>-
>-    var set = exposed[0].rhs.value;
>-    // Could be a list or a string.
>-    if (typeof set == "string") {
>-        set = [ set ];
>+    if (exposed && exposed.length) {
>+        var set = exposed[0].rhs.value;
>+        // Could be a list or a string.
>+        if (typeof set == "string") {
>+            set = [ set ];
>+        }
>+        result = new Set(set);
>+    }
>+    if (result && result.has("Worker")) {
>+        result.delete("Worker");
>+        result.add("DedicatedWorker");
>+        result.add("ServiceWorker");
>+        result.add("SharedWorker");
>     }
>-    return set;
>+    return result;
> }
> 
> function exposed_in(globals) {
>     if ('document' in self) {
>-        return globals.indexOf("Window") >= 0;
>+        return globals.has("Window");
>     }
>     if ('DedicatedWorkerGlobalScope' in self &&
>         self instanceof DedicatedWorkerGlobalScope) {
>-        return globals.indexOf("Worker") >= 0 ||
>-               globals.indexOf("DedicatedWorker") >= 0;
>+        return globals.has("DedicatedWorker");
>     }
>     if ('SharedWorkerGlobalScope' in self &&
>         self instanceof SharedWorkerGlobalScope) {
>-        return globals.indexOf("Worker") >= 0 ||
>-               globals.indexOf("SharedWorker") >= 0;
>+        return globals.has("SharedWorker");
>     }
>     if ('ServiceWorkerGlobalScope' in self &&
>         self instanceof ServiceWorkerGlobalScope) {
>-        return globals.indexOf("Worker") >= 0 ||
>-               globals.indexOf("ServiceWorker") >= 0;
>+        return globals.has("ServiceWorker");
>     }
>     throw new IdlHarnessError("Unexpected global object");
> }
>@@ -627,27 +789,7 @@ IdlArray.prototype.test = function()
> 
>     // First merge in all the partial interfaces and implements statements we
>     // encountered.
>-    this.partials.forEach(function(parsed_idl)
>-    {
>-        if (!(parsed_idl.name in this.members)
>-            || !(this.members[parsed_idl.name] instanceof IdlInterface
>-                 || this.members[parsed_idl.name] instanceof IdlDictionary))
>-        {
>-            throw new IdlHarnessError(`Partial ${parsed_idl.type} ${parsed_idl.name} with no original ${parsed_idl.type}`);
>-        }
>-        if (parsed_idl.extAttrs)
>-        {
>-            parsed_idl.extAttrs.forEach(function(extAttr)
>-            {
>-                this.members[parsed_idl.name].extAttrs.push(extAttr);
>-            }.bind(this));
>-        }
>-        parsed_idl.members.forEach(function(member)
>-        {
>-            this.members[parsed_idl.name].members.push(new IdlInterfaceMember(member));
>-        }.bind(this));
>-    }.bind(this));
>-    this.partials = [];
>+    this.collapse_partials();
> 
>     for (var lhs in this["implements"])
>     {
>@@ -683,13 +825,28 @@ IdlArray.prototype.test = function()
>     }
>     this["includes"] = {};
> 
>+    // Assert B defined for A : B
>+    for (const member of Object.values(this.members).filter(m => m.base)) {
>+        const lhs = member.name;
>+        const rhs = member.base;
>+        if (!(rhs in this.members)) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${rhs} is undefined.`);
>+        const lhs_is_interface = this.members[lhs] instanceof IdlInterface;
>+        const rhs_is_interface = this.members[rhs] instanceof IdlInterface;
>+        if (rhs_is_interface != lhs_is_interface) {
>+            if (!lhs_is_interface) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${lhs} is not an interface.`);
>+            if (!rhs_is_interface) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${rhs} is not an interface.`);
>+        }
>+        // Check for circular dependencies.
>+        member.get_inheritance_stack();
>+    }
>+
>     Object.getOwnPropertyNames(this.members).forEach(function(memberName) {
>         var member = this.members[memberName];
>         if (!(member instanceof IdlInterface)) {
>             return;
>         }
> 
>-        var globals = exposure_set(member, ["Window"]);
>+        var globals = exposure_set(member);
>         member.exposed = exposed_in(globals);
>         member.exposureSet = globals;
>     }.bind(this));
>@@ -700,14 +857,104 @@ IdlArray.prototype.test = function()
>         this.members[name].test();
>         if (name in this.objects)
>         {
>-            this.objects[name].forEach(function(str)
>+            const objects = this.objects[name];
>+            if (!objects || !Array.isArray(objects)) {
>+                throw new IdlHarnessError(`Invalid or empty objects for member ${name}`);
>+            }
>+            objects.forEach(function(str)
>             {
>+                if (!this.members[name] || !(this.members[name] instanceof IdlInterface)) {
>+                    throw new IdlHarnessError(`Invalid object member name ${name}`);
>+                }
>                 this.members[name].test_object(str);
>             }.bind(this));
>         }
>     }
> };
> 
>+//@}
>+IdlArray.prototype.collapse_partials = function()
>+//@{
>+{
>+    const testedPartials = new Map();
>+    this.partials.forEach(function(parsed_idl)
>+    {
>+        const originalExists = parsed_idl.name in this.members
>+            && (this.members[parsed_idl.name] instanceof IdlInterface
>+                || this.members[parsed_idl.name] instanceof IdlDictionary
>+                || this.members[parsed_idl.name] instanceof IdlNamespace);
>+
>+        let partialTestName = parsed_idl.name;
>+        if (!parsed_idl.untested) {
>+            // Ensure unique test name in case of multiple partials.
>+            let partialTestCount = 1;
>+            if (testedPartials.has(parsed_idl.name)) {
>+                partialTestCount += testedPartials.get(parsed_idl.name);
>+                partialTestName = `${partialTestName}[${partialTestCount}]`;
>+            }
>+            testedPartials.set(parsed_idl.name, partialTestCount);
>+
>+            test(function () {
>+                assert_true(originalExists, `Original ${parsed_idl.type} should be defined`);
>+
>+                var expected = IdlInterface;
>+                switch (parsed_idl.type) {
>+                    case 'interface': expected = IdlInterface; break;
>+                    case 'dictionary': expected = IdlDictionary; break;
>+                    case 'namespace': expected = IdlNamespace; break;
>+                }
>+                assert_true(
>+                    expected.prototype.isPrototypeOf(this.members[parsed_idl.name]),
>+                    `Original ${parsed_idl.name} definition should have type ${parsed_idl.type}`);
>+            }.bind(this), `Partial ${parsed_idl.type} ${partialTestName}: original ${parsed_idl.type} defined`);
>+        }
>+        if (!originalExists) {
>+            // Not good.. but keep calm and carry on.
>+            return;
>+        }
>+
>+        if (parsed_idl.extAttrs)
>+        {
>+            // Special-case "Exposed". Must be a subset of original interface's exposure.
>+            // Exposed on a partial is the equivalent of having the same Exposed on all nested members.
>+            // See https://github.com/heycam/webidl/issues/154 for discrepency between Exposed and
>+            // other extended attributes on partial interfaces.
>+            const exposureAttr = parsed_idl.extAttrs.find(a => a.name === "Exposed");
>+            if (exposureAttr) {
>+                if (!parsed_idl.untested) {
>+                    test(function () {
>+                        const partialExposure = exposure_set(parsed_idl);
>+                        const memberExposure = exposure_set(this.members[parsed_idl.name]);
>+                        partialExposure.forEach(name => {
>+                            if (!memberExposure || !memberExposure.has(name)) {
>+                                throw new IdlHarnessError(
>+                                    `Partial ${parsed_idl.name} ${parsed_idl.type} is exposed to '${name}', the original ${parsed_idl.type} is not.`);
>+                            }
>+                        });
>+                    }.bind(this), `Partial ${parsed_idl.type} ${partialTestName}: valid exposure set`);
>+                }
>+                parsed_idl.members.forEach(function (member) {
>+                    member.extAttrs.push(exposureAttr);
>+                }.bind(this));
>+            }
>+
>+            parsed_idl.extAttrs.forEach(function(extAttr)
>+            {
>+                // "Exposed" already handled above.
>+                if (extAttr.name === "Exposed") {
>+                    return;
>+                }
>+                this.members[parsed_idl.name].extAttrs.push(extAttr);
>+            }.bind(this));
>+        }
>+        parsed_idl.members.forEach(function(member)
>+        {
>+            this.members[parsed_idl.name].members.push(new IdlInterfaceMember(member));
>+        }.bind(this));
>+    }.bind(this));
>+    this.partials = [];
>+}
>+
> //@}
> IdlArray.prototype.assert_type_is = function(value, type)
> //@{
>@@ -762,7 +1009,7 @@ IdlArray.prototype.assert_type_is = function(value, type)
>         return;
>     }
> 
>-    if (type.sequence)
>+    if (type.generic === "sequence")
>     {
>         assert_true(Array.isArray(value), "should be an Array");
>         if (!value.length)
>@@ -1111,6 +1358,10 @@ IdlInterface.prototype.get_inheritance_stack = function() {
>         var base = this.array.members[idl_interface.base];
>         if (!base) {
>             throw new Error(idl_interface.type + " " + idl_interface.base + " not found (inherited by " + idl_interface.name + ")");
>+        } else if (stack.indexOf(base) > -1) {
>+            stack.push(base);
>+            let dep_chain = stack.map(i => i.name).join(',');
>+            throw new IdlHarnessError(`${this.name} has a circular dependency: ${dep_chain}`);
>         }
>         idl_interface = base;
>         stack.push(idl_interface);
>@@ -1206,7 +1457,7 @@ IdlInterface.prototype.test = function()
>     }
> 
>     if (!this.exposed) {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             assert_false(this.name in self);
>         }.bind(this), this.name + " interface: existence and properties of interface object");
>         return;
>@@ -1232,7 +1483,7 @@ IdlInterface.prototype.test = function()
> IdlInterface.prototype.test_self = function()
> //@{
> {
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         // This function tests WebIDL as of 2015-01-13.
> 
>@@ -1339,7 +1590,7 @@ IdlInterface.prototype.test_self = function()
>     }.bind(this), this.name + " interface: existence and properties of interface object");
> 
>     if (!this.is_callback()) {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             // This function tests WebIDL as of 2014-10-25.
>             // https://heycam.github.io/webidl/#es-interface-call
> 
>@@ -1366,7 +1617,7 @@ IdlInterface.prototype.test_self = function()
>     }
> 
>     if (!this.is_callback() || this.has_constants()) {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             // This function tests WebIDL as of 2015-11-17.
>             // https://heycam.github.io/webidl/#interface-object
> 
>@@ -1391,7 +1642,7 @@ IdlInterface.prototype.test_self = function()
> 
> 
>     if (this.has_extended_attribute("LegacyWindowAlias")) {
>-        test(function()
>+        subsetTestByKey(this.name, test, function()
>         {
>             var aliasAttrs = this.extAttrs.filter(function(o) { return o.name === "LegacyWindowAlias"; });
>             if (aliasAttrs.length > 1) {
>@@ -1400,7 +1651,7 @@ IdlInterface.prototype.test_self = function()
>             if (this.is_callback()) {
>                 throw new IdlHarnessError("Invalid IDL: LegacyWindowAlias extended attribute on non-interface " + this.name);
>             }
>-            if (this.exposureSet.indexOf("Window") === -1) {
>+            if (!this.exposureSet.has("Window")) {
>                 throw new IdlHarnessError("Invalid IDL: LegacyWindowAlias extended attribute on " + this.name + " which is not exposed in Window");
>             }
>             // TODO: when testing of [NoInterfaceObject] interfaces is supported,
>@@ -1443,7 +1694,7 @@ IdlInterface.prototype.test_self = function()
>     }
>     // TODO: Test named constructors if I find any interfaces that have them.
> 
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         // This function tests WebIDL as of 2015-01-21.
>         // https://heycam.github.io/webidl/#interface-object
>@@ -1493,8 +1744,6 @@ IdlInterface.prototype.test_self = function()
>         // object.
>         // "Otherwise, if A is declared to inherit from another interface, then
>         // return the interface prototype object for the inherited interface.
>-        // "Otherwise, if A is declared with the [LegacyArrayClass] extended
>-        // attribute, then return %ArrayPrototype%.
>         // "Otherwise, return %ObjectPrototype%.
>         //
>         // "In the ECMAScript binding, the DOMException type has some additional
>@@ -1517,9 +1766,6 @@ IdlInterface.prototype.test_self = function()
>                     !this.array
>                          .members[inherit_interface]
>                          .has_extended_attribute("NoInterfaceObject");
>-            } else if (this.has_extended_attribute('LegacyArrayClass')) {
>-                inherit_interface = 'Array';
>-                inherit_interface_has_interface_object = true;
>             } else if (this.name === "DOMException") {
>                 inherit_interface = 'Error';
>                 inherit_interface_has_interface_object = true;
>@@ -1575,7 +1821,7 @@ IdlInterface.prototype.test_self = function()
>         this.test_immutable_prototype("interface prototype object", self[this.name].prototype);
>     }
> 
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         if (this.is_callback() && !this.has_constants()) {
>             return;
>@@ -1611,7 +1857,7 @@ IdlInterface.prototype.test_self = function()
>     }.bind(this), this.name + ' interface: existence and properties of interface prototype object\'s "constructor" property');
> 
> 
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         if (this.is_callback() && !this.has_constants()) {
>             return;
>@@ -1671,7 +1917,6 @@ IdlInterface.prototype.test_self = function()
>                           this.name + '.prototype should not have @@unscopables');
>         }
>     }.bind(this), this.name + ' interface: existence and properties of interface prototype object\'s @@unscopables property');
>-
> };
> 
> //@}
>@@ -1682,7 +1927,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         return;
>     }
> 
>-    test(function(t) {
>+    subsetTestByKey(this.name, test, function(t) {
>         var originalValue = Object.getPrototypeOf(obj);
>         var newValue = Object.create(null);
> 
>@@ -1705,7 +1950,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         "of " + type + " - setting to a new value via Object.setPrototypeOf " +
>         "should throw a TypeError");
> 
>-    test(function(t) {
>+    subsetTestByKey(this.name, test, function(t) {
>         var originalValue = Object.getPrototypeOf(obj);
>         var newValue = Object.create(null);
> 
>@@ -1732,7 +1977,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         "of " + type + " - setting to a new value via __proto__ " +
>         "should throw a TypeError");
> 
>-    test(function(t) {
>+    subsetTestByKey(this.name, test, function(t) {
>         var originalValue = Object.getPrototypeOf(obj);
>         var newValue = Object.create(null);
> 
>@@ -1753,7 +1998,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         "of " + type + " - setting to a new value via Reflect.setPrototypeOf " +
>         "should return false");
> 
>-    test(function() {
>+    subsetTestByKey(this.name, test, function() {
>         var originalValue = Object.getPrototypeOf(obj);
> 
>         Object.setPrototypeOf(obj, originalValue);
>@@ -1761,7 +2006,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         "of " + type + " - setting to its original value via Object.setPrototypeOf " +
>         "should not throw");
> 
>-    test(function() {
>+    subsetTestByKey(this.name, test, function() {
>         var originalValue = Object.getPrototypeOf(obj);
> 
>         obj.__proto__ = originalValue;
>@@ -1769,7 +2014,7 @@ IdlInterface.prototype.test_immutable_prototype = function(type, obj)
>         "of " + type + " - setting to its original value via __proto__ " +
>         "should not throw");
> 
>-    test(function() {
>+    subsetTestByKey(this.name, test, function() {
>         var originalValue = Object.getPrototypeOf(obj);
> 
>         assert_true(Reflect.setPrototypeOf(obj, originalValue));
>@@ -1786,7 +2031,7 @@ IdlInterface.prototype.test_member_const = function(member)
>         throw new IdlHarnessError("Internal error: test_member_const called without any constants");
>     }
> 
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         assert_own_property(self, this.name,
>                             "self does not have own property " + format_value(this.name));
>@@ -1812,7 +2057,7 @@ IdlInterface.prototype.test_member_const = function(member)
> 
>     // "In addition, a property with the same characteristics must
>     // exist on the interface prototype object."
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         assert_own_property(self, this.name,
>                             "self does not have own property " + format_value(this.name));
>@@ -1843,7 +2088,10 @@ IdlInterface.prototype.test_member_const = function(member)
> IdlInterface.prototype.test_member_attribute = function(member)
> //@{
>   {
>-    var a_test = async_test(this.name + " interface: attribute " + member.name);
>+    if (!shouldRunSubTest(this.name)) {
>+        return;
>+    }
>+    var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: attribute " + member.name);
>     a_test.step(function()
>     {
>         if (this.is_callback() && !this.has_constants()) {
>@@ -1861,7 +2109,12 @@ IdlInterface.prototype.test_member_attribute = function(member)
>                 "The interface object must have a property " +
>                 format_value(member.name));
>             a_test.done();
>-        } else if (this.is_global()) {
>+            return;
>+        }
>+
>+        this.do_member_unscopable_asserts(member);
>+
>+        if (this.is_global()) {
>             assert_own_property(self, member.name,
>                 "The global object must have a property " +
>                 format_value(member.name));
>@@ -1922,20 +2175,18 @@ IdlInterface.prototype.test_member_attribute = function(member)
>               // since it will call done() on a_test.
>               this.do_interface_attribute_asserts(self[this.name].prototype, member, a_test);
>             }
>-
>         }
>     }.bind(this));
>-
>-    test(function () {
>-        this.do_member_unscopable_asserts(member);
>-    }.bind(this), 'Unscopable handled correctly for ' + member.name + ' property on ' + this.name);
> };
> 
> //@}
> IdlInterface.prototype.test_member_operation = function(member)
> //@{
> {
>-    var a_test = async_test(this.name + " interface: operation " + member.name +
>+    if (!shouldRunSubTest(this.name)) {
>+        return;
>+    }
>+    var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: operation " + member.name +
>                             "(" + member.arguments.map(
>                                 function(m) {return m.idlType.idlType; } ).join(", ")
>                             +")");
>@@ -1991,16 +2242,9 @@ IdlInterface.prototype.test_member_operation = function(member)
>                     "interface prototype object missing non-static operation");
>             memberHolderObject = self[this.name].prototype;
>         }
>+        this.do_member_unscopable_asserts(member);
>         this.do_member_operation_asserts(memberHolderObject, member, a_test);
>     }.bind(this));
>-
>-    test(function () {
>-        this.do_member_unscopable_asserts(member);
>-    }.bind(this),
>-         'Unscopable handled correctly for ' + member.name + "(" +
>-         member.arguments.map(
>-             function(m) {return m.idlType.idlType; } ).join(", ")
>-         + ")" + ' on ' + this.name);
> };
> 
> IdlInterface.prototype.do_member_unscopable_asserts = function(member)
>@@ -2051,15 +2295,13 @@ IdlInterface.prototype.do_member_operation_asserts = function(memberHolderObject
>     // behavior is as follows . . ."
>     assert_equals(typeof memberHolderObject[member.name], "function",
>                   "property must be a function");
>-    // "The value of the Function objectâs âlengthâ property is
>-    // a Number determined as follows:
>-    // ". . .
>-    // "Return the length of the shortest argument list of the
>-    // entries in S."
>-    assert_equals(memberHolderObject[member.name].length,
>-        minOverloadLength(this.members.filter(function(m) {
>-            return m.type == "operation" && m.name == member.name;
>-        })),
>+
>+    const ctors = this.members.filter(function(m) {
>+        return m.type == "operation" && m.name == member.name;
>+    });
>+    assert_equals(
>+        memberHolderObject[member.name].length,
>+        minOverloadLength(ctors),
>         "property has wrong .length");
> 
>     // Make some suitable arguments
>@@ -2119,10 +2361,11 @@ IdlInterface.prototype.add_iterable_members = function(member)
> };
> 
> IdlInterface.prototype.test_to_json_operation = function(memberHolderObject, member) {
>-    var instanceName = memberHolderObject.constructor.name;
>+    var instanceName = memberHolderObject && memberHolderObject.constructor.name
>+        || member.name + " object";
>     if (member.has_extended_attribute("Default")) {
>-        var map = this.default_to_json_operation();
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>+            var map = this.default_to_json_operation();
>             var json = memberHolderObject.toJSON();
>             map.forEach(function(type, k) {
>                 assert_true(k in json, "property " + JSON.stringify(k) + " should be present in the output of " + this.name + ".prototype.toJSON()");
>@@ -2135,7 +2378,7 @@ IdlInterface.prototype.test_to_json_operation = function(memberHolderObject, mem
>             }, this);
>         }.bind(this), "Test default toJSON operation of " + instanceName);
>     } else {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             assert_true(this.array.is_json_type(member.idlType), JSON.stringify(member.idlType) + " is not an appropriate return value for the toJSON operation of " + instanceName);
>             this.array.assert_type_is(memberHolderObject.toJSON(), member.idlType);
>         }.bind(this), "Test toJSON operation of " + instanceName);
>@@ -2147,8 +2390,8 @@ IdlInterface.prototype.test_member_iterable = function(member)
> //@{
> {
>     var interfaceName = this.name;
>-    var isPairIterator = member.idlType instanceof Array;
>-    test(function()
>+    var isPairIterator = member.idlType.length === 2;
>+    subsetTestByKey(this.name, test, function()
>     {
>         var descriptor = Object.getOwnPropertyDescriptor(self[interfaceName].prototype, Symbol.iterator);
>         assert_true(descriptor.writable, "property should be writable");
>@@ -2158,11 +2401,11 @@ IdlInterface.prototype.test_member_iterable = function(member)
>     }, "Testing Symbol.iterator property of iterable interface " + interfaceName);
> 
>     if (isPairIterator) {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             assert_equals(self[interfaceName].prototype[Symbol.iterator], self[interfaceName].prototype["entries"], "entries method is not the same as @@iterator");
>         }, "Testing pair iterable interface " + interfaceName);
>     } else {
>-        test(function() {
>+        subsetTestByKey(this.name, test, function() {
>             ["entries", "keys", "values", "forEach", Symbol.Iterator].forEach(function(property) {
>                 assert_equals(self[interfaceName].prototype[property], Array.prototype[property], property + " function is not the same as Array one");
>             });
>@@ -2174,7 +2417,7 @@ IdlInterface.prototype.test_member_iterable = function(member)
> IdlInterface.prototype.test_member_stringifier = function(member)
> //@{
> {
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         if (this.is_callback() && !this.has_constants()) {
>             return;
>@@ -2259,7 +2502,7 @@ IdlInterface.prototype.test_members = function()
>         }
> 
>         if (!exposed_in(exposure_set(member, this.exposureSet))) {
>-            test(function() {
>+            subsetTestByKey(this.name, test, function() {
>                 // It's not exposed, so we shouldn't find it anywhere.
>                 assert_false(member.name in self[this.name],
>                              "The interface object must not have a property " +
>@@ -2380,7 +2623,7 @@ IdlInterface.prototype.test_primary_interface_of = function(desc, obj, exception
>     if (!this.has_extended_attribute("NoInterfaceObject")
>     && (typeof obj != expected_typeof || obj instanceof Object))
>     {
>-        test(function()
>+        subsetTestByKey(this.name, test, function()
>         {
>             assert_equals(exception, null, "Unexpected exception when evaluating object");
>             assert_equals(typeof obj, expected_typeof, "wrong typeof object");
>@@ -2402,7 +2645,7 @@ IdlInterface.prototype.test_primary_interface_of = function(desc, obj, exception
>     // "The class string of a platform object that implements one or more
>     // interfaces must be the identifier of the primary interface of the
>     // platform object."
>-    test(function()
>+    subsetTestByKey(this.name, test, function()
>     {
>         assert_equals(exception, null, "Unexpected exception when evaluating object");
>         assert_equals(typeof obj, expected_typeof, "wrong typeof object");
>@@ -2420,6 +2663,9 @@ IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expect
> {
>     // TODO: Indexed and named properties, more checks on interface members
>     this.already_tested = true;
>+    if (!shouldRunSubTest(this.name)) {
>+        return;
>+    }
> 
>     for (var i = 0; i < this.members.length; i++)
>     {
>@@ -2428,14 +2674,15 @@ IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expect
>             continue;
>         }
>         if (!exposed_in(exposure_set(member, this.exposureSet))) {
>-            test(function() {
>+            subsetTestByKey(this.name, test, function() {
>+                assert_equals(exception, null, "Unexpected exception when evaluating object");
>                 assert_false(member.name in obj);
>             }.bind(this), this.name + " interface: " + desc + ' must not have property "' + member.name + '"');
>             continue;
>         }
>         if (member.type == "attribute" && member.isUnforgeable)
>         {
>-            var a_test = async_test(this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
>+            var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
>             a_test.step(function() {
>                 assert_equals(exception, null, "Unexpected exception when evaluating object");
>                 assert_equals(typeof obj, expected_typeof, "wrong typeof object");
>@@ -2447,7 +2694,7 @@ IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expect
>                  member.name &&
>                  member.isUnforgeable)
>         {
>-            var a_test = async_test(this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
>+            var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
>             a_test.step(function()
>             {
>                 assert_equals(exception, null, "Unexpected exception when evaluating object");
>@@ -2467,7 +2714,7 @@ IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expect
>             {
>                 described_name += "(" + member.arguments.map(arg => arg.idlType.idlType).join(", ") + ")";
>             }
>-            test(function()
>+            subsetTestByKey(this.name, test, function()
>             {
>                 assert_equals(exception, null, "Unexpected exception when evaluating object");
>                 assert_equals(typeof obj, expected_typeof, "wrong typeof object");
>@@ -2513,7 +2760,7 @@ IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expect
>         // TODO: Test passing arguments of the wrong type.
>         if (member.type == "operation" && member.name && member.arguments.length)
>         {
>-            var a_test = async_test( this.name + " interface: calling " + member.name +
>+            var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: calling " + member.name +
>             "(" + member.arguments.map(function(m) { return m.idlType.idlType; }).join(", ") +
>             ") on " + desc + " with too few arguments must throw TypeError");
>             a_test.step(function()
>@@ -2804,5 +3051,198 @@ function IdlTypedef(obj)
> 
> IdlTypedef.prototype = Object.create(IdlObject.prototype);
> 
>+/// IdlNamespace ///
>+function IdlNamespace(obj)
>+//@{
>+{
>+    this.name = obj.name;
>+    this.extAttrs = obj.extAttrs;
>+    this.untested = obj.untested;
>+    /** A back-reference to our IdlArray. */
>+    this.array = obj.array;
>+
>+    /** An array of IdlInterfaceMembers. */
>+    this.members = obj.members.map(m => new IdlInterfaceMember(m));
>+}
>+//@}
>+
>+IdlNamespace.prototype = Object.create(IdlObject.prototype);
>+
>+IdlNamespace.prototype.do_member_operation_asserts = function (memberHolderObject, member, a_test)
>+//@{
>+{
>+    var desc = Object.getOwnPropertyDescriptor(memberHolderObject, member.name);
>+
>+    assert_false("get" in desc, "property should not have a getter");
>+    assert_false("set" in desc, "property should not have a setter");
>+    assert_equals(
>+        desc.writable,
>+        !member.isUnforgeable,
>+        "property should be writable if and only if not unforgeable");
>+    assert_true(desc.enumerable, "property should be enumerable");
>+    assert_equals(
>+        desc.configurable,
>+        !member.isUnforgeable,
>+        "property should be configurable if and only if not unforgeable");
>+
>+    assert_equals(
>+        typeof memberHolderObject[member.name],
>+        "function",
>+         "property must be a function");
>+
>+    assert_equals(
>+        memberHolderObject[member.name].length,
>+        minOverloadLength(this.members.filter(function(m) {
>+            return m.type == "operation" && m.name == member.name;
>+        })),
>+        "operation has wrong .length");
>+    a_test.done();
>+}
>+//@}
>+
>+IdlNamespace.prototype.test_member_operation = function(member)
>+//@{
>+{
>+    if (!shouldRunSubTest(this.name)) {
>+        return;
>+    }
>+    var args = member.arguments.map(function(a) {
>+        var s = a.idlType.idlType;
>+        if (a.variadic) {
>+            s += '...';
>+        }
>+        return s;
>+    }).join(", ");
>+    var a_test = subsetTestByKey(
>+        this.name,
>+        async_test,
>+        this.name + ' namespace: operation ' + member.name + '(' + args + ')');
>+    a_test.step(function() {
>+        assert_own_property(
>+            self[this.name],
>+            member.name,
>+            'namespace object missing operation ' + format_value(member.name));
>+
>+        this.do_member_operation_asserts(self[this.name], member, a_test);
>+    }.bind(this));
>+};
>+//@}
>+
>+IdlNamespace.prototype.test_member_attribute = function (member)
>+//@{
>+{
>+    if (!shouldRunSubTest(this.name)) {
>+        return;
>+    }
>+    var a_test = subsetTestByKey(
>+        this.name,
>+        async_test,
>+        this.name + ' namespace: attribute ' + member.name);
>+    a_test.step(function()
>+    {
>+        assert_own_property(
>+            self[this.name],
>+            member.name,
>+            this.name + ' does not have property ' + format_value(member.name));
>+
>+        var desc = Object.getOwnPropertyDescriptor(self[this.name], member.name);
>+        assert_equals(desc.set, undefined, "setter must be undefined for namespace members");
>+        a_test.done();
>+    }.bind(this));
>+};
>+//@}
>+
>+IdlNamespace.prototype.test = function ()
>+//@{
>+{
>+    /**
>+     * TODO(lukebjerring): Assert:
>+     * - "Note that unlike interfaces or dictionaries, namespaces do not create types."
>+     * - "Of the extended attributes defined in this specification, only the
>+     *     [Exposed] and [SecureContext] extended attributes are applicable to namespaces."
>+     * - "Namespaces must be annotated with the [Exposed] extended attribute."
>+     */
>+
>+    for (const v of Object.values(this.members)) {
>+        switch (v.type) {
>+
>+        case 'operation':
>+            this.test_member_operation(v);
>+            break;
>+
>+        case 'attribute':
>+            this.test_member_attribute(v);
>+            break;
>+
>+        default:
>+            throw 'Invalid namespace member ' + v.name + ': ' + v.type + ' not supported';
>+        }
>+    };
>+};
>+//@}
>+
> }());
>+
>+/**
>+ * idl_test is a promise_test wrapper that handles the fetching of the IDL,
>+ * avoiding repetitive boilerplate.
>+ *
>+ * @param {String|String[]} srcs Spec name(s) for source idl files (fetched from
>+ *      /interfaces/{name}.idl).
>+ * @param {String|String[]} deps Spec name(s) for dependency idl files (fetched
>+ *      from /interfaces/{name}.idl). Order is important - dependencies from
>+ *      each source will only be included if they're already know to be a
>+ *      dependency (i.e. have already been seen).
>+ * @param {Function} setup_func Function for extra setup of the idl_array, such
>+ *      as adding objects. Do not call idl_array.test() in the setup; it is
>+ *      called by this function (idl_test).
>+ */
>+function idl_test(srcs, deps, idl_setup_func) {
>+    return promise_test(function (t) {
>+        var idl_array = new IdlArray();
>+        srcs = (srcs instanceof Array) ? srcs : [srcs] || [];
>+        deps = (deps instanceof Array) ? deps : [deps] || [];
>+        var setup_error = null;
>+        return Promise.all(
>+            srcs.concat(deps).map(function(spec) {
>+                return fetch_spec(spec);
>+            }))
>+            .then(function(idls) {
>+                for (var i = 0; i < srcs.length; i++) {
>+                    idl_array.add_idls(idls[i]);
>+                }
>+                for (var i = srcs.length; i < srcs.length + deps.length; i++) {
>+                    idl_array.add_dependency_idls(idls[i]);
>+                }
>+            })
>+            .then(function() {
>+                if (idl_setup_func) {
>+                    return idl_setup_func(idl_array, t);
>+                }
>+            })
>+            .catch(function(e) { setup_error = e || 'IDL setup failed.'; })
>+            .then(function () {
>+                var error = setup_error;
>+                try {
>+                    idl_array.test(); // Test what we can.
>+                } catch (e) {
>+                    // If testing fails hard here, the original setup error
>+                    // is more likely to be the real cause.
>+                    error = error || e;
>+                }
>+                if (error) {
>+                    throw error;
>+                }
>+            });
>+    }, 'idl_test setup');
>+}
>+
>+/**
>+ * fetch_spec is a shorthand for a Promise that fetches the spec's content.
>+ */
>+function fetch_spec(spec) {
>+    return fetch('/interfaces/' + spec + '.idl').then(function (r) {
>+        return r.text();
>+    });
>+}
> // vim: set expandtab shiftwidth=4 tabstop=4 foldmarker=@{,@} foldmethod=marker:
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/CHANGELOG.md b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/CHANGELOG.md
>new file mode 100644
>index 0000000000000000000000000000000000000000..91e22275e0700e1f553148c7f5414d7ccaf0fe33
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/CHANGELOG.md
>@@ -0,0 +1,292 @@
>+# Change Log
>+
>+## [v10.2.1](https://github.com/w3c/webidl2.js/tree/v10.2.1) (2018-03-09)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v10.2.0...v10.2.1)
>+
>+**Merged pull requests:**
>+
>+- Optimise tokenisation and whitespace skipping [\#139](https://github.com/w3c/webidl2.js/pull/139) ([ricea](https://github.com/ricea))
>+- refactor: small syntax changes [\#137](https://github.com/w3c/webidl2.js/pull/137) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v10.2.0](https://github.com/w3c/webidl2.js/tree/v10.2.0) (2018-01-30)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v10.1.0...v10.2.0)
>+
>+**Merged pull requests:**
>+
>+- Type on union idlType [\#135](https://github.com/w3c/webidl2.js/pull/135) ([saschanaz](https://github.com/saschanaz))
>+- feat: add argument/return type [\#134](https://github.com/w3c/webidl2.js/pull/134) ([saschanaz](https://github.com/saschanaz))
>+- feat: add dictionary/typedef-type [\#133](https://github.com/w3c/webidl2.js/pull/133) ([saschanaz](https://github.com/saschanaz))
>+- feat: add const-type for idlTypes  [\#132](https://github.com/w3c/webidl2.js/pull/132) ([saschanaz](https://github.com/saschanaz))
>+- feat: add types on idlTypes [\#131](https://github.com/w3c/webidl2.js/pull/131) ([saschanaz](https://github.com/saschanaz))
>+- Auto acquisition for parser result changes [\#130](https://github.com/w3c/webidl2.js/pull/130) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v10.1.0](https://github.com/w3c/webidl2.js/tree/v10.1.0) (2018-01-19)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v10.0.0...v10.1.0)
>+
>+**Closed issues:**
>+
>+- Support `raises` and `setraises` [\#128](https://github.com/w3c/webidl2.js/issues/128)
>+- Support `legacycaller` [\#127](https://github.com/w3c/webidl2.js/issues/127)
>+- Improve "No semicolon after enum" message [\#119](https://github.com/w3c/webidl2.js/issues/119)
>+
>+**Merged pull requests:**
>+
>+- Let error messages include the current definition name [\#129](https://github.com/w3c/webidl2.js/pull/129) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v10.0.0](https://github.com/w3c/webidl2.js/tree/v10.0.0) (2017-12-20)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v9.0.0...v10.0.0)
>+
>+**Closed issues:**
>+
>+-  Always return an array for idlType, etc. [\#113](https://github.com/w3c/webidl2.js/issues/113)
>+- Maintain writer.js or not? [\#109](https://github.com/w3c/webidl2.js/issues/109)
>+
>+**Merged pull requests:**
>+
>+- Remove typeExtAttrs from docs [\#124](https://github.com/w3c/webidl2.js/pull/124) ([saschanaz](https://github.com/saschanaz))
>+- Remove iterator documentation [\#123](https://github.com/w3c/webidl2.js/pull/123) ([saschanaz](https://github.com/saschanaz))
>+- Maintain writer.js [\#122](https://github.com/w3c/webidl2.js/pull/122) ([saschanaz](https://github.com/saschanaz))
>+- BREAKING CHANGE: remove deprecated iterator operation [\#121](https://github.com/w3c/webidl2.js/pull/121) ([saschanaz](https://github.com/saschanaz))
>+- Use for-of on tests [\#120](https://github.com/w3c/webidl2.js/pull/120) ([saschanaz](https://github.com/saschanaz))
>+- docs$README$: iterables ildType is always array [\#118](https://github.com/w3c/webidl2.js/pull/118) ([marcoscaceres](https://github.com/marcoscaceres))
>+
>+## [v9.0.0](https://github.com/w3c/webidl2.js/tree/v9.0.0) (2017-11-30)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v8.1.0...v9.0.0)
>+
>+**Closed issues:**
>+
>+- Code quality [\#116](https://github.com/w3c/webidl2.js/issues/116)
>+- Unable to parse HTMLAllCollection interface [\#114](https://github.com/w3c/webidl2.js/issues/114)
>+- Add support for mixin syntax [\#112](https://github.com/w3c/webidl2.js/issues/112)
>+- Whitespace issues [\#111](https://github.com/w3c/webidl2.js/issues/111)
>+
>+**Merged pull requests:**
>+
>+- Consistent array type for iterable.idlType [\#117](https://github.com/w3c/webidl2.js/pull/117) ([saschanaz](https://github.com/saschanaz))
>+-  Revert "chore: drop Node 6 support $\#102$" [\#115](https://github.com/w3c/webidl2.js/pull/115) ([TimothyGu](https://github.com/TimothyGu))
>+
>+## [v8.1.0](https://github.com/w3c/webidl2.js/tree/v8.1.0) (2017-11-03)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v8.0.1...v8.1.0)
>+
>+**Closed issues:**
>+
>+- Extended Attributes `rhs` should always be there [\#96](https://github.com/w3c/webidl2.js/issues/96)
>+
>+**Merged pull requests:**
>+
>+- Always add rhs property [\#110](https://github.com/w3c/webidl2.js/pull/110) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v8.0.1](https://github.com/w3c/webidl2.js/tree/v8.0.1) (2017-11-03)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v8.0.0...v8.0.1)
>+
>+**Fixed bugs:**
>+
>+- Comment order parsing bug  [\#107](https://github.com/w3c/webidl2.js/issues/107)
>+
>+**Merged pull requests:**
>+
>+- Remove m postfix from all\_ws [\#108](https://github.com/w3c/webidl2.js/pull/108) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v8.0.0](https://github.com/w3c/webidl2.js/tree/v8.0.0) (2017-11-03)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v7.0.0...v8.0.0)
>+
>+**Closed issues:**
>+
>+- Remove creators support [\#100](https://github.com/w3c/webidl2.js/issues/100)
>+- Add mixin support [\#92](https://github.com/w3c/webidl2.js/issues/92)
>+
>+**Merged pull requests:**
>+
>+- Support mixins + includes statements [\#105](https://github.com/w3c/webidl2.js/pull/105) ([saschanaz](https://github.com/saschanaz))
>+- chore: drop Node 6 support [\#102](https://github.com/w3c/webidl2.js/pull/102) ([marcoscaceres](https://github.com/marcoscaceres))
>+- BREAKING CHANGE: drop creator support [\#101](https://github.com/w3c/webidl2.js/pull/101) ([saschanaz](https://github.com/saschanaz))
>+- Normalize some whitespace to pass wpt's lint [\#99](https://github.com/w3c/webidl2.js/pull/99) ([foolip](https://github.com/foolip))
>+
>+## [v7.0.0](https://github.com/w3c/webidl2.js/tree/v7.0.0) (2017-10-27)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v6.1.0...v7.0.0)
>+
>+**Closed issues:**
>+
>+- Type conversion on default values is destructive  [\#94](https://github.com/w3c/webidl2.js/issues/94)
>+- extended attribute structure missing type [\#89](https://github.com/w3c/webidl2.js/issues/89)
>+
>+**Merged pull requests:**
>+
>+-  BREAKING CHANGE: argument + default types should be string [\#95](https://github.com/w3c/webidl2.js/pull/95) ([marcoscaceres](https://github.com/marcoscaceres))
>+
>+## [v6.1.0](https://github.com/w3c/webidl2.js/tree/v6.1.0) (2017-10-23)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v6.0.1...v6.1.0)
>+
>+**Merged pull requests:**
>+
>+- feat: give extended attributes a type [\#90](https://github.com/w3c/webidl2.js/pull/90) ([marcoscaceres](https://github.com/marcoscaceres))
>+
>+## [v6.0.1](https://github.com/w3c/webidl2.js/tree/v6.0.1) (2017-10-18)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v6.0.0...v6.0.1)
>+
>+**Closed issues:**
>+
>+- Enum values should be objects [\#86](https://github.com/w3c/webidl2.js/issues/86)
>+
>+**Merged pull requests:**
>+
>+- Use ES2015 syntax for tests [\#88](https://github.com/w3c/webidl2.js/pull/88) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v6.0.0](https://github.com/w3c/webidl2.js/tree/v6.0.0) (2017-10-17)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v5.0.0...v6.0.0)
>+
>+**Merged pull requests:**
>+
>+- BREAKING CHANGE: ret enum value as object [\#87](https://github.com/w3c/webidl2.js/pull/87) ([marcoscaceres](https://github.com/marcoscaceres))
>+
>+## [v5.0.0](https://github.com/w3c/webidl2.js/tree/v5.0.0) (2017-10-17)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v4.2.0...v5.0.0)
>+
>+**Closed issues:**
>+
>+- Unable to parse annotated types in generics [\#83](https://github.com/w3c/webidl2.js/issues/83)
>+- Drop support for Node 4, move to 6 LTS [\#82](https://github.com/w3c/webidl2.js/issues/82)
>+
>+**Merged pull requests:**
>+
>+- BREAKING CHANGE: Use ES2015 syntax [\#84](https://github.com/w3c/webidl2.js/pull/84) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v4.2.0](https://github.com/w3c/webidl2.js/tree/v4.2.0) (2017-10-16)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v4.1.0...v4.2.0)
>+
>+**Closed issues:**
>+
>+- Remove legacy caller support [\#78](https://github.com/w3c/webidl2.js/issues/78)
>+- Should report error for using duplicate names [\#77](https://github.com/w3c/webidl2.js/issues/77)
>+
>+**Merged pull requests:**
>+
>+- Check duplicated names [\#80](https://github.com/w3c/webidl2.js/pull/80) ([saschanaz](https://github.com/saschanaz))
>+- Remove legacycaller [\#79](https://github.com/w3c/webidl2.js/pull/79) ([saschanaz](https://github.com/saschanaz))
>+- Add "sequence" property to IDL Type AST definition [\#76](https://github.com/w3c/webidl2.js/pull/76) ([lerouche](https://github.com/lerouche))
>+
>+## [v4.1.0](https://github.com/w3c/webidl2.js/tree/v4.1.0) (2017-07-04)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v4.0.0...v4.1.0)
>+
>+**Closed issues:**
>+
>+- Parsing error for annonated inner types of generic types [\#71](https://github.com/w3c/webidl2.js/issues/71)
>+
>+**Merged pull requests:**
>+
>+- Support TypeWithExtendedAttributes on generics [\#75](https://github.com/w3c/webidl2.js/pull/75) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v4.0.0](https://github.com/w3c/webidl2.js/tree/v4.0.0) (2017-06-27)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v3.0.2...v4.0.0)
>+
>+**Closed issues:**
>+
>+- Remove serializer-related productions [\#73](https://github.com/w3c/webidl2.js/issues/73)
>+- Records don't seem to be working right [\#72](https://github.com/w3c/webidl2.js/issues/72)
>+- Document namespace member output [\#59](https://github.com/w3c/webidl2.js/issues/59)
>+
>+**Merged pull requests:**
>+
>+- BREAKING CHANGE: remove serializers $closes \#73$ [\#74](https://github.com/w3c/webidl2.js/pull/74) ([marcoscaceres](https://github.com/marcoscaceres))
>+- Add documentation for namespaces [\#70](https://github.com/w3c/webidl2.js/pull/70) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v3.0.2](https://github.com/w3c/webidl2.js/tree/v3.0.2) (2017-05-29)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v3.0.1...v3.0.2)
>+
>+**Closed issues:**
>+
>+- Whitespace issues [\#64](https://github.com/w3c/webidl2.js/issues/64)
>+
>+**Merged pull requests:**
>+
>+- Test for latest LTS/stable node versions [\#69](https://github.com/w3c/webidl2.js/pull/69) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v3.0.1](https://github.com/w3c/webidl2.js/tree/v3.0.1) (2017-05-18)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v2.4.0...v3.0.1)
>+
>+**Closed issues:**
>+
>+- Is array syntax dead? [\#66](https://github.com/w3c/webidl2.js/issues/66)
>+- Remove exceptions support [\#65](https://github.com/w3c/webidl2.js/issues/65)
>+
>+**Merged pull requests:**
>+
>+- Fix whitespace error on parsing extended attributes [\#68](https://github.com/w3c/webidl2.js/pull/68) ([saschanaz](https://github.com/saschanaz))
>+- Remove deprecated IDL arrays and exceptions [\#67](https://github.com/w3c/webidl2.js/pull/67) ([saschanaz](https://github.com/saschanaz))
>+
>+## [v2.4.0](https://github.com/w3c/webidl2.js/tree/v2.4.0) (2017-04-12)
>+[Full Changelog](https://github.com/w3c/webidl2.js/compare/v2.1.0...v2.4.0)
>+
>+**Closed issues:**
>+
>+- Add support for Annotated Types [\#60](https://github.com/w3c/webidl2.js/issues/60)
>+- Question: Convert WebIDL -\> Javascript [\#56](https://github.com/w3c/webidl2.js/issues/56)
>+- Get Robin to give us push permissions on npm [\#54](https://github.com/w3c/webidl2.js/issues/54)
>+- Add support for records [\#53](https://github.com/w3c/webidl2.js/issues/53)
>+- module not supported? [\#52](https://github.com/w3c/webidl2.js/issues/52)
>+- Add support for namespaces [\#51](https://github.com/w3c/webidl2.js/issues/51)
>+- Export is not AMD compatible [\#48](https://github.com/w3c/webidl2.js/issues/48)
>+- Can't represent large constants [\#21](https://github.com/w3c/webidl2.js/issues/21)
>+
>+**Merged pull requests:**
>+
>+- Update webidl2.js [\#63](https://github.com/w3c/webidl2.js/pull/63) ([tqeto](https://github.com/tqeto))
>+- Remove support for MapClass $no longer valid in WebIDL$ [\#62](https://github.com/w3c/webidl2.js/pull/62) ([dontcallmedom](https://github.com/dontcallmedom))
>+- Add support for annotated types [\#61](https://github.com/w3c/webidl2.js/pull/61) ([dontcallmedom](https://github.com/dontcallmedom))
>+- Support namespaces [\#58](https://github.com/w3c/webidl2.js/pull/58) ([saschanaz](https://github.com/saschanaz))
>+- Add support for records [\#57](https://github.com/w3c/webidl2.js/pull/57) ([TimothyGu](https://github.com/TimothyGu))
>+- Refactor [\#50](https://github.com/w3c/webidl2.js/pull/50) ([marcoscaceres](https://github.com/marcoscaceres))
>+- feat$lib$: add AMD export support $closes \#48$ [\#49](https://github.com/w3c/webidl2.js/pull/49) ([marcoscaceres](https://github.com/marcoscaceres))
>+
>+## [v2.1.0](https://github.com/w3c/webidl2.js/tree/v2.1.0) (2016-08-12)
>+**Closed issues:**
>+
>+- Exception when parsing test/syntax/idl/typedef.widl [\#46](https://github.com/w3c/webidl2.js/issues/46)
>+- Wrong jsondiffpatch location [\#42](https://github.com/w3c/webidl2.js/issues/42)
>+- 'npm install' fails on building microtime [\#40](https://github.com/w3c/webidl2.js/issues/40)
>+- Can't represent union types in typedefs [\#38](https://github.com/w3c/webidl2.js/issues/38)
>+- tokenise assumes a specific property enumeration order [\#27](https://github.com/w3c/webidl2.js/issues/27)
>+- Add support for iterable\<\>, maplike\<\>, setlike\<\> declarations [\#24](https://github.com/w3c/webidl2.js/issues/24)
>+- WebIDL2 fails to parse `attribute Promise\<DOMString\>\[\] baz` [\#19](https://github.com/w3c/webidl2.js/issues/19)
>+- Support for ExtendedAttributeIdentList $current editor's draft$ [\#18](https://github.com/w3c/webidl2.js/issues/18)
>+- No Licensing Information [\#17](https://github.com/w3c/webidl2.js/issues/17)
>+- how to regenerate w3c idl files ? [\#14](https://github.com/w3c/webidl2.js/issues/14)
>+- What is lib/writer.js [\#13](https://github.com/w3c/webidl2.js/issues/13)
>+- Numerous tests are failing [\#7](https://github.com/w3c/webidl2.js/issues/7)
>+- Add support for missing types in ServiceWorker [\#5](https://github.com/w3c/webidl2.js/issues/5)
>+- How can I parse just a function? [\#3](https://github.com/w3c/webidl2.js/issues/3)
>+- Parser throws on nullable array of nullable array [\#2](https://github.com/w3c/webidl2.js/issues/2)
>+- Parser throws on nullable array of any [\#1](https://github.com/w3c/webidl2.js/issues/1)
>+
>+**Merged pull requests:**
>+
>+- Fix "default": undefined [\#47](https://github.com/w3c/webidl2.js/pull/47) ([mkwtys](https://github.com/mkwtys))
>+- Replace expect.js with expct [\#45](https://github.com/w3c/webidl2.js/pull/45) ([halton](https://github.com/halton))
>+- Correct jsondiffpatch location. [\#44](https://github.com/w3c/webidl2.js/pull/44) ([halton](https://github.com/halton))
>+- Bump microtime to 2.1.1 [\#43](https://github.com/w3c/webidl2.js/pull/43) ([halton](https://github.com/halton))
>+- Expand writer support [\#39](https://github.com/w3c/webidl2.js/pull/39) ([markandrus](https://github.com/markandrus))
>+- Accept wider $but still incomplete$ set of allowed syntax for extended attributes [\#37](https://github.com/w3c/webidl2.js/pull/37) ([mlogan](https://github.com/mlogan))
>+- Add test for callback with multiple arguments. [\#36](https://github.com/w3c/webidl2.js/pull/36) ([tobie](https://github.com/tobie))
>+- Iterables [\#34](https://github.com/w3c/webidl2.js/pull/34) ([motiz88](https://github.com/motiz88))
>+- Allow trailing comma in enum value lists, per spec [\#33](https://github.com/w3c/webidl2.js/pull/33) ([motiz88](https://github.com/motiz88))
>+- Allow typedefs within interfaces $behind an opt-in flag$ [\#32](https://github.com/w3c/webidl2.js/pull/32) ([motiz88](https://github.com/motiz88))
>+- In draft [\#31](https://github.com/w3c/webidl2.js/pull/31) ([othree](https://github.com/othree))
>+- Add support for extended attributes identifier lists [\#29](https://github.com/w3c/webidl2.js/pull/29) ([tobie](https://github.com/tobie))
>+- Make `attribute Promise\<T\>\[\] attr;` work. [\#26](https://github.com/w3c/webidl2.js/pull/26) ([jyasskin](https://github.com/jyasskin))
>+- Parse required dictionary fields. [\#25](https://github.com/w3c/webidl2.js/pull/25) ([jyasskin](https://github.com/jyasskin))
>+- Define the WebIDL2 property on self rather than window. [\#23](https://github.com/w3c/webidl2.js/pull/23) ([Ms2ger](https://github.com/Ms2ger))
>+- Teach WebIDL2 to parse \[\] default values. [\#22](https://github.com/w3c/webidl2.js/pull/22) ([jyasskin](https://github.com/jyasskin))
>+- Support ID list in extended attributes [\#20](https://github.com/w3c/webidl2.js/pull/20) ([othree](https://github.com/othree))
>+- Make sure that `sequence` property of idl types is set to false if the type is actually `sequence`. [\#16](https://github.com/w3c/webidl2.js/pull/16) ([tobie](https://github.com/tobie))
>+- Parametrized [\#15](https://github.com/w3c/webidl2.js/pull/15) ([tobie](https://github.com/tobie))
>+- Add promise support [\#12](https://github.com/w3c/webidl2.js/pull/12) ([tobie](https://github.com/tobie))
>+- Remove broken coverage support from travis for now. [\#11](https://github.com/w3c/webidl2.js/pull/11) ([tobie](https://github.com/tobie))
>+- Add support for \[MapClass$type, type$\]. [\#10](https://github.com/w3c/webidl2.js/pull/10) ([tobie](https://github.com/tobie))
>+- Incorporate tests from widlproc\[1\] and remove dependency on said project. [\#9](https://github.com/w3c/webidl2.js/pull/9) ([tobie](https://github.com/tobie))
>+- README incorrectly recommended updating the widlproc submodule. [\#8](https://github.com/w3c/webidl2.js/pull/8) ([tobie](https://github.com/tobie))
>+- Fix bug where instrumented version of webidl2 was loaded. [\#6](https://github.com/w3c/webidl2.js/pull/6) ([tobie](https://github.com/tobie))
>+- Use https:// instead of git:// [\#4](https://github.com/w3c/webidl2.js/pull/4) ([Manishearth](https://github.com/Manishearth))
>+
>+
>+
>+\* *This Change Log was automatically generated by [github_changelog_generator](https://github.com/skywinder/Github-Changelog-Generator)*
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/README.md b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/README.md
>index 5d128ed27ca87cc76f15caeb63c9ceec0d8aa790..9a8f3f8e9c1dfbe897e8a6d8267cf89ec00cb20a 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/README.md
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/README.md
>@@ -1,7 +1,7 @@
> 
> # WebIDL 2
> 
>-[![NPM version](https://badge.fury.io/js/webidl2.png)](http://badge.fury.io/js/webidl2)
>+[![NPM version](https://badge.fury.io/js/webidl2.svg)](http://badge.fury.io/js/webidl2)
> 
> ## Purpose
> 
>@@ -10,26 +10,6 @@ you don't know what that is, then you probably don't need it. It is meant to be
> both in Node and in the browser (the parser likely works in other JS environments, but
> not the test suite).
> 
>-### What of v1?
>-
>-There was a previous incarnation of this project. I had written it in the most quick
>-and dirty manner that was handy because I required it as a dependency in an experiment.
>-As these things tend to happen, some people started using that, which then had to be
>-maintained. But since it was not built on solid foundations, it was painful to keep
>-up to date with the specification, which is a bit of a moving target.
>-
>-So I started from scratch. Compared to the previous version (which used a parser generator)
>-this one is about 6x less code (which translates to 4x smaller minified or 2x smaller
>-minizipped) and 4x faster. The test suite is reasonably complete (95% coverage), much more
>-than previously. This version is up to date with WebIDL, rather than a couple years' behind.
>-It also has *far* better error reporting.
>-
>-The AST you get from parsing is very similar to the one you got in v1, but some adjustments
>-have been made in order to be more systematic, and to map better to what's actually in the spec
>-now. If you used v1, you will need to tweak your code but the result ought to be simpler and
>-you ought to be able to be a fair bit less defensive against irregularities in the way
>-information is represented.
>-
> ## Installation
> 
> Just the usual. For Node:
>@@ -46,7 +26,6 @@ In the browser:
> 
> ## Documentation
> 
>-
> The API to WebIDL2 is trivial: you parse a string of WebIDL and it returns a syntax tree.
> 
> ### Parsing
>@@ -66,23 +45,6 @@ In the browser:
> </script>
> ```
> 
>-### Advanced Parsing
>-
>-`parse()` can optionally accept a second parameter, an options object, which can be used to
>-modify parsing behavior.
>-
>-The following options are recognized:
>-```JS
>-{
>-  allowNestedTypedefs: false
>-}
>-```
>-
>-And their meanings are as follows:
>-
>-* `allowNestedTypedefs`: Boolean indicating whether the parser should accept `typedef`s as valid members of `interface`s.
>-This is non-standard syntax and therefore the default is `false`.
>-
> ### Errors
> 
> When there is a syntax error in the WebIDL, it throws an exception object with the following
>@@ -103,7 +65,7 @@ The `parse()` method returns a tree object representing the parse tree of the ID
> Comment and white space are not represented in the AST.
> 
> The root of this object is always an array of definitions (where definitions are
>-any of interfaces, exceptions, callbacks, etc. â anything that can occur at the root
>+any of interfaces, dictionaries, callbacks, etc. â anything that can occur at the root
> of the IDL).
> 
> ### IDL Type
>@@ -114,18 +76,18 @@ attached to a field called `idlType`:
> 
> ```JS
> {
>-  "array": false,
>+  "type": "attribute-type",
>   "generic": null,
>-  "idlType": "void",
>+  "idlType": "unsigned short",
>   "nullable": false,
>   "union": false,
>+  "extAttrs": [...]
> }
> ```
> 
> Where the fields are as follows:
> 
>-* `array`: Either `false` to indicate that it is not an array, or a number for the level of
>-  array nesting.
>+* `type`: String indicating where this type is used. Can be `null` if not applicable.
> * `generic`: String indicating the generic type (e.g. "Promise", "sequence"). `null`
>   otherwise.
> * `idlType`: Can be different things depending on context. In most cases, this will just
>@@ -135,41 +97,10 @@ Where the fields are as follows:
>   description for the type in the sequence, the eventual value of the promise, etc.
> * `nullable`: Boolean indicating whether this is nullable or not.
> * `union`: Boolean indicating whether this is a union type or not.
>-
>-#### Interactions between `nullable` and `array`
>-
>-A more complex data model for our AST would likely represent `Foo[][][]` as a series of
>-nested types four levels deep with three anonymous array types eventually containing a
>-`Foo` type. But experience shows that such structures are cumbersome to use, and so we
>-have a simpler model in which the depth of the array is specified with the `array` field.
>-
>-This is all fine and well, and in the vast majority of cases is actually simpler. But it
>-does run afoul of cases in which it is necessary to distinguish between `Foo[][][]?`,
>-`Foo?[][][]`, `Foo[][]?[]`, or even `Foo?[]?[]?[]?`.
>-
>-For this, when a type is an array type an additional `nullableArray` field is made available
>-that captures which of the arrays contain nullable elements. It contains booleans that are
>-true if the given array depth contains nullable elements, and false otherwise (mapping that to
>-the syntax, and item is true if there is a `?` preceding the `[]`). These examples ought to
>-clarify the model:
>-
>-    Foo[][][]?
>-        -> nullable: true
>-        -> nullableArray: [false, false, false]
>-    Foo?[][][]
>-        -> nullable: false
>-        -> nullableArray: [true, false, false]
>-    Foo[][]?[]
>-        -> nullable: false
>-        -> nullableArray: [false, false, true]
>-    Foo?[]?[]?[]?
>-        -> nullable: true
>-        -> nullableArray: [true, true, true]
>-
>-Of particular importance, please note that the overall type is only `nullable` if there is
>-a `?` at the end.
>+* `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
> ### Interface
>+
> Interfaces look like this:
> 
> ```JS
>@@ -193,7 +124,7 @@ Interfaces look like this:
> The fields are as follows:
> 
> * `type`: Always "interface".
>-* `name`: The name of the interface
>+* `name`: The name of the interface.
> * `partial`: A boolean indicating whether it's a partial interface.
> * `members`: An array of interface members (attributes, operations, etc.). Empty if there are none.
> * `inheritance`: A string giving the name of an interface this one inherits from, `null` otherwise.
>@@ -201,6 +132,56 @@ The fields are as follows:
>   sense.
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
>+### Interface mixins
>+
>+Interfaces mixins look like this:
>+
>+```JS
>+{
>+  "type": "interface mixin",
>+  "name": "Animal",
>+  "partial": false,
>+  "members": [...],
>+  "extAttrs": [...]
>+}, {
>+  "type": "interface mixin",
>+  "name": "Human",
>+  "partial": false,
>+  "members": [...],
>+  "extAttrs": [...]
>+}
>+```
>+
>+The fields are as follows:
>+
>+* `type`: Always "interface mixin".
>+* `name`: The name of the interface mixin.
>+* `partial`: A boolean indicating whether it's a partial interface mixin.
>+* `members`: An array of interface members (attributes, operations, etc.). Empty if there are none.
>+* `extAttrs`: A list of [extended attributes](#extended-attributes).
>+
>+### Namespace
>+
>+Namespaces look like this:
>+
>+```JS
>+{
>+  "type": "namespace",
>+  "name": "Console",
>+  "partial": false,
>+  "members": [...],
>+  "extAttrs": [...]
>+}
>+```
>+
>+The fields are as follows:
>+
>+* `type`: Always "namespace".
>+* `name`: The name of the namespace.
>+* `partial`: A boolean indicating whether it's a partial namespace.
>+* `members`: An array of namespace members (attributes and operations). Empty if there are none.
>+* `extAttrs`: A list of [extended attributes](#extended-attributes).
>+
> ### Callback Interfaces
> 
> These are captured by the same structure as [Interfaces](#interface) except that
>@@ -215,12 +196,13 @@ A callback looks like this:
>   "type": "callback",
>   "name": "AsyncOperationCallback",
>   "idlType": {
>+    "type": "return-type",
>     "sequence": false,
>     "generic": null,
>     "nullable": false,
>-    "array": false,
>     "union": false,
>-    "idlType": "void"
>+    "idlType": "void",
>+    "extAttrs": []
>   },
>   "arguments": [...],
>   "extAttrs": []
>@@ -249,12 +231,13 @@ A dictionary looks like this:
>     "name": "fillPattern",
>     "required": false,
>     "idlType": {
>+      "type": "dictionary-type",
>       "sequence": false,
>       "generic": null,
>       "nullable": true,
>-      "array": false,
>       "union": false,
>-      "idlType": "DOMString"
>+      "idlType": "DOMString",
>+      "extAttrs": [...]
>     },
>     "extAttrs": [],
>     "default": {
>@@ -285,47 +268,6 @@ All the members are fields as follows:
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> * `default`: A [default value](#default-and-const-values), absent if there is none.
> 
>-### Exception
>-
>-An exception looks like this:
>-
>-```JS
>-{
>-  "type": "exception",
>-  "name": "HierarchyRequestError",
>-  "members": [{
>-    "type": "field",
>-    "name": "code",
>-    "idlType": {
>-      "sequence": false,
>-      "generic": null,
>-      "nullable": false,
>-      "array": false,
>-      "union": false,
>-      "idlType": "unsigned short"
>-    },
>-    "extAttrs": []
>-  }],
>-  "inheritance": "DOMException",
>-  "extAttrs": []
>-}
>-```
>-
>-The fields are as follows:
>-
>-* `type`: Always "exception".
>-* `name`: The exception name.
>-* `members`: An array of members (constants or fields, where fields are described below).
>-* `inheritance`: A string indicating which exception is being inherited from, `null` otherwise.
>-* `extAttrs`: A list of [extended attributes](#extended-attributes).
>-
>-Members that aren't [constants](#constants) have the following fields:
>-
>-* `type`: Always "field".
>-* `name`: The field's name.
>-* `idlType`: An [IDL Type](#idl-type) describing what field's type.
>-* `extAttrs`: A list of [extended attributes](#extended-attributes).
>-
> ### Enum
> 
> An enum looks like this:
>@@ -335,9 +277,9 @@ An enum looks like this:
>   "type": "enum",
>   "name": "MealType",
>   "values": [
>-    "rice",
>-    "noodles",
>-    "other"
>+    { "type": "string", "value": "rice" },
>+    { "type": "string", "value": "noodles" },
>+    { "type": "string", "value": "other" }
>   ],
>   "extAttrs": []
> }
>@@ -347,7 +289,7 @@ The fields are as follows:
> 
> * `type`: Always "enum".
> * `name`: The enum's name.
>-* `value`: An array of values (strings).
>+* `values`: An array of values.
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
> ### Typedef
>@@ -357,21 +299,22 @@ A typedef looks like this:
> ```JS
> {
>   "type": "typedef",
>-  "typeExtAttrs": [],
>   "idlType": {
>+    "type": "typedef-type",
>     "sequence": true,
>     "generic": "sequence",
>     "nullable": false,
>-    "array": false,
>     "union": false,
>     "idlType": {
>+      "type": "typedef-type",
>       "sequence": false,
>       "generic": null,
>       "nullable": false,
>-      "array": false,
>       "union": false,
>-      "idlType": "Point"
>-    }
>+      "idlType": "Point",
>+      "extAttrs": [...]
>+    },
>+    "extAttrs": [...]
>   },
>   "name": "PointSequence",
>   "extAttrs": []
>@@ -385,8 +328,6 @@ The fields are as follows:
> * `name`: The typedef's name.
> * `idlType`: An [IDL Type](#idl-type) describing what typedef's type.
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
>-* `typeExtAttrs`: A list of [extended attributes](#extended-attributes) that apply to the 
>-type rather than to the typedef as a whole.
> 
> ### Implements
> 
>@@ -408,6 +349,26 @@ The fields are as follows:
> * `implements`: The interface that is being implemented by the target.
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
>+### Includes
>+
>+An includes definition looks like this:
>+
>+```JS
>+{
>+  "type": "includes",
>+  "target": "Node",
>+  "includes": "EventTarget",
>+  "extAttrs": []
>+}
>+```
>+
>+The fields are as follows:
>+
>+* `type`: Always "includes".
>+* `target`: The interface that includes an interface mixin.
>+* `includes`: The interface mixin that is being included by the target.
>+* `extAttrs`: A list of [extended attributes](#extended-attributes).
>+
> ### Operation Member
> 
> An operation looks like this:
>@@ -416,18 +377,17 @@ An operation looks like this:
>   "type": "operation",
>   "getter": false,
>   "setter": false,
>-  "creator": false,
>   "deleter": false,
>-  "legacycaller": false,
>   "static": false,
>   "stringifier": false,
>   "idlType": {
>+    "type": "return-type",
>     "sequence": false,
>     "generic": null,
>     "nullable": false,
>-    "array": false,
>     "union": false,
>-    "idlType": "void"
>+    "idlType": "void",
>+    "extAttrs": []
>   },
>   "name": "intersection",
>   "arguments": [{
>@@ -435,12 +395,13 @@ An operation looks like this:
>     "variadic": true,
>     "extAttrs": [],
>     "idlType": {
>+      "type": "argument-type",
>       "sequence": false,
>       "generic": null,
>       "nullable": false,
>-      "array": false,
>       "union": false,
>-      "idlType": "long"
>+      "idlType": "long",
>+      "extAttrs": [...]
>     },
>     "name": "ints"
>   }],
>@@ -453,9 +414,7 @@ The fields are as follows:
> * `type`: Always "operation".
> * `getter`: True if a getter operation.
> * `setter`: True if a setter operation.
>-* `creator`: True if a creator operation.
> * `deleter`: True if a deleter operation.
>-* `legacycaller`: True if a legacycaller operation.
> * `static`: True if a static operation.
> * `stringifier`: True if a stringifier operation.
> * `idlType`: An [IDL Type](#idl-type) of what the operation returns. If a stringifier, may be absent.
>@@ -475,12 +434,13 @@ An attribute member looks like this:
>   "inherit": false,
>   "readonly": false,
>   "idlType": {
>+    "type": "attribute-type",
>     "sequence": false,
>     "generic": null,
>     "nullable": false,
>-    "array": false,
>     "union": false,
>-    "idlType": "RegExp"
>+    "idlType": "RegExp",
>+    "extAttrs": [...]
>   },
>   "name": "regexp",
>   "extAttrs": []
>@@ -506,7 +466,15 @@ A constant member looks like this:
> {
>   "type": "const",
>   "nullable": false,
>-  "idlType": "boolean",
>+  "idlType": {
>+    "type": "const-type",
>+    "sequence": false,
>+    "generic": null,
>+    "nullable": false,
>+    "union": false,
>+    "idlType": "boolean"
>+    "extAttrs": []
>+  },
>   "name": "DEBUG",
>   "value": {
>     "type": "boolean",
>@@ -520,132 +488,11 @@ The fields are as follows:
> 
> * `type`: Always "const".
> * `nullable`: Whether its type is nullable.
>-* `idlType`: The type of the constant (a simple type, the type name).
>+* `idlType`: An [IDL Type](#idl-type) of the constant that represents a simple type, the type name.
> * `name`: The name of the constant.
> * `value`: The constant value as described by [Const Values](#default-and-const-values)
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
>-### Serializer Member
>-
>-Serializers come in many shapes, which are best understood by looking at the
>-examples below that map the IDL to the produced AST.
>-
>-```JS
>-// serializer;
>-{
>-  "type": "serializer",
>-  "extAttrs": []
>-}
>-
>-// serializer DOMString serialize();
>-{
>-  "type": "serializer",
>-  "idlType": {
>-    "sequence": false,
>-    "generic": null,
>-    "nullable": false,
>-    "array": false,
>-    "union": false,
>-    "idlType": "DOMString"
>-  },
>-  "operation": {
>-    "name": "serialize",
>-    "arguments": []
>-  },
>-  "extAttrs": []
>-}
>-
>-// serializer = { from, to, amount, description };
>-{
>-  "type": "serializer",
>-  "patternMap": true,
>-  "names": [
>-    "from",
>-    "to",
>-    "amount",
>-    "description"
>-  ],
>-  "extAttrs": []
>-}
>-
>-// serializer = number;
>-{
>-  "type": "serializer",
>-  "name": "number",
>-  "extAttrs": []
>-}
>-
>-// serializer = [ name, number ];
>-{
>-  "type": "serializer",
>-  "patternList": true,
>-  "names": [
>-    "name",
>-    "number"
>-  ],
>-  "extAttrs": []
>-}
>-
>-```
>-
>-The common fields are as follows:
>-
>-* `type`: Always "serializer".
>-* `extAttrs`: A list of [extended attributes](#extended-attributes).
>-
>-For a simple serializer, that's all there is. If the serializer is an operation, it will
>-have:
>-
>-* `idlType`: An [IDL Type](#idl-type) describing what the serializer returns.
>-* `operation`: An object with the following fields:
>-    * `name`: The name of the operation.
>-    * `arguments`: An array of [arguments](#arguments) for the operation.
>-
>-If the serializer is a pattern map:
>-
>-* `patternMap`: Always true.
>-* `names`: An array of names in the pattern map.
>-
>-If the serializer is a pattern list:
>-
>-* `patternList`: Always true.
>-* `names`: An array of names in the pattern list.
>-
>-Finally, if the serializer is a named serializer:
>-
>-* `name`: The serializer's name.
>-
>-### Iterator Member
>-
>-Iterator members look like this
>-
>-```JS
>-{
>-  "type": "iterator",
>-  "getter": false,
>-  "setter": false,
>-  "creator": false,
>-  "deleter": false,
>-  "legacycaller": false,
>-  "static": false,
>-  "stringifier": false,
>-  "idlType": {
>-    "sequence": false,
>-    "generic": null,
>-    "nullable": false,
>-    "array": false,
>-    "union": false,
>-    "idlType": "Session2"
>-  },
>-  "iteratorObject": "SessionIterator",
>-  "extAttrs": []
>-}
>-```
>-
>-* `type`: Always "iterator".
>-* `iteratorObject`: The string on the right-hand side; absent if there isn't one.
>-* the rest: same as on [operations](#operation-member).
>-
> ### Arguments
> 
> The arguments (e.g. for an operation) look like this:
>@@ -657,12 +504,13 @@ The arguments (e.g. for an operation) look like this:
>     "variadic": true,
>     "extAttrs": [],
>     "idlType": {
>+      "type": "argument-type",
>       "sequence": false,
>       "generic": null,
>       "nullable": false,
>-      "array": false,
>       "union": false,
>-      "idlType": "long"
>+      "idlType": "long",
>+      "extAttrs": [...]
>     },
>     "name": "ints"
>   }]
>@@ -686,6 +534,7 @@ Extended attributes are arrays of items that look like this:
>   "extAttrs": [{
>     "name": "TreatNullAs",
>     "arguments": null,
>+    "type": "extended-attribute",
>     "rhs": {
>       "type": "identifier",
>       "value": "EmptyString"
>@@ -703,10 +552,9 @@ The fields are as follows:
>   whereas the lack thereof will yield a `null`. If there is an `rhs` field then
>   they are the right-hand side's arguments, otherwise they apply to the extended
>   attribute directly.
>+* `type`: Always `"extended-attribute"`.
> * `rhs`: If there is a right-hand side, this will capture its `type` (which can be
>   "identifier" or "identifier-list") and its `value`.
>-* `typePair`: If the extended attribute is a `MapClass` this will capture the
>-  map's key type and value type respectively.
> 
> ### Default and Const Values
> 
>@@ -717,7 +565,7 @@ values, all of which have the following fields:
> 
> For string, number, boolean, and sequence:
> 
>-* `value`: The value of the given type. For sequence, the only possible value is `[]`.
>+* `value`: The value of the given type, as a string. For sequence, the only possible value is `[]`.
> 
> For Infinity:
> 
>@@ -739,21 +587,13 @@ These appear as members of interfaces that look like this:
> The fields are as follows:
> 
> * `type`: Always one of "iterable", "legacyiterable", "maplike" or "setlike".
>-* `idlType`: An [IDL Type](#idl-type) (or an array of two types) representing the declared type arguments.
>+* `idlType`: An array with one or more [IDL Types](#idl-type) representing the declared type arguments.
> * `readonly`: Whether the maplike or setlike is declared as read only.
> * `extAttrs`: A list of [extended attributes](#extended-attributes).
> 
> 
> ## Testing
> 
>-In order to run the tests you need to ensure that the widlproc submodule inside `test` is
>-initialized and up to date:
>-
>-```Bash
>-git submodule init
>-git submodule update
>-```
>-
> ### Running
> 
> The test runs with mocha and expect.js. Normally, running mocha in the root directory
>@@ -787,8 +627,3 @@ In order to test in the browser, get inside `test/web` and run `make-web-tests.j
> will generate a `browser-tests.html` file that you can open in a browser. As of this
> writing tests pass in the latest Firefox, Chrome, Opera, and Safari. Testing on IE
> and older versions will happen progressively.
>-
>-## TODO
>-
>-* add some tests to address coverage limitations
>-* add a push API for processors that need to process things like comments
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/index.html b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/index.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..9897d8572f22a0e66ba6c4704606d94fb66bba59
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/index.html
>@@ -0,0 +1,55 @@
>+<!DOCTYPE html>
>+<html>
>+<head>
>+<title>WebIDL 2 Checker</title>
>+
>+<script src='../lib/webidl2.js'></script>
>+<script>
>+let parserResult = undefined;
>+
>+function formatParserOutput() {
>+  const outputEl = document.getElementById('webidl-checker-output');
>+  if (parserResult) {
>+    const prettyPrintEl = document.getElementById('pretty-print');
>+    outputEl.innerText = JSON.stringify(parserResult, null, prettyPrintEl.checked ? 2 : null);
>+  } else {
>+    outputEl.innerText = '';
>+  }
>+}
>+
>+function checkWebIDL(textToCheck) {
>+  const validation = document.getElementById('webidl-checker-validation');
>+  parserResult = null;
>+  try {
>+    parserResult = WebIDL2.parse(textToCheck);
>+    validation.innerText = 'WebIDL parsed successfully!';
>+  } catch (e) {
>+    validation.innerText = 'Exception while parsing WebIDL. See JavaScript console for more details.\n\n' + e.toString();
>+    // Pass it along to the JavaScript console.
>+    throw e;
>+  } finally {
>+    formatParserOutput();
>+  }
>+}
>+</script>
>+<style>
>+textarea {
>+  font-family: monospace;
>+}
>+</style>
>+</head>
>+<body>
>+<h2>WebIDL Checker</h2>
>+<p>This is an online checker for WebIDL built on the <a href="https://github.com/w3c/webidl2.js">webidl2.js</a> project.</p>
>+<p>Enter your WebIDL to check below:</p>
>+<textarea id='webidl-to-check' rows='20' cols='80'></textarea>
>+<br>
>+<input type='button' value='Check WebIDL' onclick='checkWebIDL(document.getElementById("webidl-to-check").value)'>
>+<p>Validation results:</p>
>+<textarea id='webidl-checker-validation' rows='20' cols='80'></textarea>
>+<p>Parser output:</p>
>+<textarea id='webidl-checker-output' rows='20' cols='80'></textarea>
>+<br>
>+<input type='checkbox' id='pretty-print' checked='true' onchange='formatParserOutput()'>Pretty Print
>+</body>
>+</html>
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/w3c-import.log
>new file mode 100644
>index 0000000000000000000000000000000000000000..7affc26d975007dc62b9d331e3fc257c004a9e3c
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/w3c-import.log
>@@ -0,0 +1,17 @@
>+The tests in this directory were imported from the W3C repository.
>+Do NOT modify these tests directly in WebKit.
>+Instead, create a pull request on the WPT github:
>+	https://github.com/web-platform-tests/wpt
>+
>+Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
>+
>+Do NOT modify or remove this file.
>+
>+------------------------------------------------------------------------
>+Properties requiring vendor prefixes:
>+None
>+Property values requiring vendor prefixes:
>+None
>+------------------------------------------------------------------------
>+List of files:
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/checker/index.html
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/w3c-import.log
>index 7802428012cb75dd353343c508594c85e3bc1cb3..0bc9abba1930c96d42d023741af1ea5c757c16bd 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/webidl2.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/webidl2.js
>index 0c9a1faacf7c7403bc5b0dbe12f524aefc9f3840..ef519c09df6d6da812fcbba57c7ca0f475af1ed5 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/webidl2.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/webidl2.js
>@@ -1,33 +1,161 @@
> "use strict";
> 
> (() => {
>+  // These regular expressions use the sticky flag so they will only match at
>+  // the current location (ie. the offset of lastIndex).
>+  const tokenRe = {
>+    // This expression uses a lookahead assertion to catch false matches
>+    // against integers early.
>+    "float": /-?(?=[0-9]*\.|[0-9]+[eE])(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][-+]?[0-9]+)?|[0-9]+[Ee][-+]?[0-9]+)/y,
>+    "integer": /-?(0([Xx][0-9A-Fa-f]+|[0-7]*)|[1-9][0-9]*)/y,
>+    "identifier": /_?[A-Za-z][0-9A-Z_a-z-]*/y,
>+    "string": /"[^"]*"/y,
>+    "whitespace": /[\t\n\r ]+/y,
>+    "comment": /((\/(\/.*|\*([^*]|\*[^\/])*\*\/)[\t\n\r ]*)+)/y,
>+    "other": /[^\t\n\r 0-9A-Za-z]/y
>+  };
>+
>+  const stringTypes = [
>+    "ByteString",
>+    "DOMString",
>+    "USVString"
>+  ];
>+
>+  const argumentNameKeywords = [
>+    "attribute",
>+    "callback",
>+    "const",
>+    "deleter",
>+    "dictionary",
>+    "enum",
>+    "getter",
>+    "includes",
>+    "inherit",
>+    "interface",
>+    "iterable",
>+    "maplike",
>+    "namespace",
>+    "partial",
>+    "required",
>+    "setlike",
>+    "setter",
>+    "static",
>+    "stringifier",
>+    "typedef",
>+    "unrestricted"
>+  ];
>+
>+  const nonRegexTerminals = [
>+    "FrozenArray",
>+    "Infinity",
>+    "NaN",
>+    "Promise",
>+    "boolean",
>+    "byte",
>+    "double",
>+    "false",
>+    "float",
>+    "implements",
>+    "legacyiterable",
>+    "long",
>+    "mixin",
>+    "null",
>+    "octet",
>+    "optional",
>+    "or",
>+    "readonly",
>+    "record",
>+    "sequence",
>+    "short",
>+    "true",
>+    "unsigned",
>+    "void"
>+  ].concat(argumentNameKeywords, stringTypes);
>+
>+  const punctuations = [
>+    "(",
>+    ")",
>+    ",",
>+    "-Infinity",
>+    "...",
>+    ":",
>+    ";",
>+    "<",
>+    "=",
>+    ">",
>+    "?",
>+    "[",
>+    "]",
>+    "{",
>+    "}"
>+  ];
>+
>   function tokenise(str) {
>     const tokens = [];
>-    const re = {
>-      "float": /^-?(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][-+]?[0-9]+)?|[0-9]+[Ee][-+]?[0-9]+)/,
>-      "integer": /^-?(0([Xx][0-9A-Fa-f]+|[0-7]*)|[1-9][0-9]*)/,
>-      "identifier": /^[A-Z_a-z][0-9A-Z_a-z-]*/,
>-      "string": /^"[^"]*"/,
>-      "whitespace": /^(?:[\t\n\r ]+|[\t\n\r ]*((\/\/.*|\/\*(.|\n|\r)*?\*\/)[\t\n\r ]*))+/,
>-      "other": /^[^\t\n\r 0-9A-Z_a-z]/
>-    };
>-    const types = ["float", "integer", "identifier", "string", "whitespace", "other"];
>-    while (str.length > 0) {
>-      let matched = false;
>-      for (var i in types) {
>-        const type = types[i];
>-        str = str.replace(re[type], tok => {
>-          tokens.push({ type, value: tok });
>-          matched = true;
>-          return "";
>-        });
>-        if (matched) break;
>+    let lastIndex = 0;
>+    let trivia = "";
>+    while (lastIndex < str.length) {
>+      const nextChar = str.charAt(lastIndex);
>+      let result = -1;
>+
>+      if (/[\t\n\r ]/.test(nextChar)) {
>+        result = attemptTokenMatch("whitespace", { noFlushTrivia: true });
>+      } else if (nextChar === '/') {
>+        result = attemptTokenMatch("comment", { noFlushTrivia: true });
>+      }
>+
>+      if (result !== -1) {
>+        trivia += tokens.pop().value;
>+      } else if (/[-0-9.]/.test(nextChar)) {
>+        result = attemptTokenMatch("float");
>+        if (result === -1) {
>+          result = attemptTokenMatch("integer");
>+        }
>+      } else if (/[A-Z_a-z]/.test(nextChar)) {
>+        result = attemptTokenMatch("identifier");
>+        const token = tokens[tokens.length - 1];
>+        if (result !== -1 && nonRegexTerminals.includes(token.value)) {
>+          token.type = token.value;
>+        }
>+      } else if (nextChar === '"') {
>+        result = attemptTokenMatch("string");
>+      }
>+
>+      for (const punctuation of punctuations) {
>+        if (str.startsWith(punctuation, lastIndex)) {
>+          tokens.push({ type: punctuation, value: punctuation, trivia });
>+          trivia = "";
>+          lastIndex += punctuation.length;
>+          result = lastIndex;
>+          break;
>+        }
>+      }
>+
>+      // other as the last try
>+      if (result === -1) {
>+        result = attemptTokenMatch("other");
>+      }
>+      if (result === -1) {
>+        throw new Error("Token stream not progressing");
>       }
>-      if (matched) continue;
>-      throw new Error("Token stream not progressing");
>+      lastIndex = result;
>     }
>     return tokens;
>-  };
>+
>+    function attemptTokenMatch(type, { noFlushTrivia } = {}) {
>+      const re = tokenRe[type];
>+      re.lastIndex = lastIndex;
>+      const result = re.exec(str);
>+      if (result) {
>+        tokens.push({ type, value: result[0], trivia });
>+        if (!noFlushTrivia) {
>+          trivia = "";
>+        }
>+        return re.lastIndex;
>+      }
>+      return -1;
>+    }
>+  }
> 
>   class WebIDLParseError {
>     constructor(str, line, input, tokens) {
>@@ -38,14 +166,17 @@
>     }
> 
>     toString() {
>-      return `${this.message}, line ${this.line} (tokens: '${this.input}')\n${JSON.stringify(this.tokens, null, 4)}`;
>+      const escapedInput = JSON.stringify(this.input);
>+      const tokens = JSON.stringify(this.tokens, null, 4);
>+      return `${this.message}, line ${this.line} (tokens: ${escapedInput})\n${tokens}`;
>     }
>   }
> 
>-  function parse(tokens, opt) {
>+  function parse(tokens) {
>     let line = 1;
>     tokens = tokens.slice();
>     const names = new Map();
>+    let current = null;
> 
>     const FLOAT = "float";
>     const INT = "integer";
>@@ -58,20 +189,39 @@
>       getter: false,
>       setter: false,
>       deleter: false,
>-      "static": false,
>+      static: false,
>       stringifier: false
>     });
> 
>+    const EMPTY_IDLTYPE = Object.freeze({
>+      generic: null,
>+      nullable: false,
>+      union: false,
>+      idlType: null,
>+      extAttrs: []
>+    });
>+
>     function error(str) {
>-      let tok = "";
>-      let numTokens = 0;
>       const maxTokens = 5;
>-      while (numTokens < maxTokens && tokens.length > numTokens) {
>-        tok += tokens[numTokens].value;
>-        numTokens++;
>+      const tok = tokens
>+        .slice(consume_position, consume_position + maxTokens)
>+        .map(t => t.trivia + t.value).join("");
>+      // Count newlines preceding the actual erroneous token
>+      if (tokens.length) {
>+        line += count(tokens[consume_position].trivia, "\n");
>       }
>-      throw new WebIDLParseError(str, line, tok, tokens.slice(0, maxTokens));
>-    };
>+
>+      let message;
>+      if (current) {
>+        message = `Got an error during or right after parsing \`${current.partial ? "partial " : ""}${current.type} ${current.name}\`: ${str}`
>+      }
>+      else {
>+        // throwing before any valid definition
>+        message = `Got an error before parsing any named definition: ${str}`;
>+      }
>+
>+      throw new WebIDLParseError(message, line, tok, tokens.slice(0, maxTokens));
>+    }
> 
>     function sanitize_name(name, type) {
>       if (names.has(name)) {
>@@ -81,587 +231,457 @@
>       return name;
>     }
> 
>-    let last_token = null;
>+    let consume_position = 0;
> 
>-    function consume(type, value) {
>-      if (!tokens.length || tokens[0].type !== type) return;
>-      if (typeof value === "undefined" || tokens[0].value === value) {
>-        last_token = tokens.shift();
>-        if (type === ID) last_token.value = last_token.value.replace(/^_/, "");
>-        return last_token;
>-      }
>-    };
>-
>-    function ws() {
>-      if (!tokens.length) return;
>-      if (tokens[0].type === "whitespace") {
>-        const t = tokens.shift();
>-        t.value.replace(/\n/g, m => {
>-          line++;
>-          return m;
>-        });
>-        return t;
>+    function probe(type) {
>+      return tokens.length > consume_position && tokens[consume_position].type === type;
>+    }
>+
>+    function consume(...candidates) {
>+      // TODO: use const when Servo updates its JS engine
>+      for (let type of candidates) {
>+        if (!probe(type)) continue;
>+        const token = tokens[consume_position];
>+        consume_position++;
>+        line += count(token.trivia, "\n");
>+        return token;
>       }
>-    };
>+    }
> 
>-    function all_ws(store, pea) { // pea == post extended attribute, tpea = same for types
>-      const t = { type: "whitespace", value: "" };
>-      while (true) {
>-        const w = ws();
>-        if (!w) break;
>-        t.value += w.value;
>+    function unescape(identifier) {
>+      return identifier.startsWith('_') ? identifier.slice(1) : identifier;
>+    }
>+
>+    function unconsume(position) {
>+      while (consume_position > position) {
>+        consume_position--;
>+        line -= count(tokens[consume_position].trivia, "\n");
>       }
>-      if (t.value.length > 0) {
>-        if (store) {
>-          let w = t.value;
>-          const re = {
>-            "ws": /^([\t\n\r ]+)/,
>-            "line-comment": /^\/\/(.*)\r?\n?/,
>-            "multiline-comment": /^\/\*((?:.|\n|\r)*?)\*\//
>-          };
>-          const wsTypes = [];
>-          for (var k in re) wsTypes.push(k);
>-          while (w.length) {
>-            let matched = false;
>-            for (var i in wsTypes) {
>-              const type = wsTypes[i];
>-              w = w.replace(re[type], (tok, m1) => {
>-                store.push({ type: type + (pea ? ("-" + pea) : ""), value: m1 });
>-                matched = true;
>-                return "";
>-              });
>-              if (matched) break;
>-            }
>-            if (matched) continue;
>-            throw new Error("Surprising white space construct."); // this shouldn't happen
>-          }
>-        }
>-        return t;
>+    }
>+
>+    function count(str, char) {
>+      let total = 0;
>+      for (let i = str.indexOf(char); i !== -1; i = str.indexOf(char, i + 1)) {
>+        ++total;
>       }
>-    };
>+      return total;
>+    }
> 
>     function integer_type() {
>       let ret = "";
>-      all_ws();
>-      if (consume(ID, "unsigned")) ret = "unsigned ";
>-      all_ws();
>-      if (consume(ID, "short")) return ret + "short";
>-      if (consume(ID, "long")) {
>+      if (consume("unsigned")) ret = "unsigned ";
>+      if (consume("short")) return ret + "short";
>+      if (consume("long")) {
>         ret += "long";
>-        all_ws();
>-        if (consume(ID, "long")) return ret + " long";
>+        if (consume("long")) return ret + " long";
>         return ret;
>       }
>       if (ret) error("Failed to parse integer type");
>-    };
>+    }
> 
>     function float_type() {
>       let ret = "";
>-      all_ws();
>-      if (consume(ID, "unrestricted")) ret = "unrestricted ";
>-      all_ws();
>-      if (consume(ID, "float")) return ret + "float";
>-      if (consume(ID, "double")) return ret + "double";
>+      if (consume("unrestricted")) ret = "unrestricted ";
>+      if (consume("float")) return ret + "float";
>+      if (consume("double")) return ret + "double";
>       if (ret) error("Failed to parse float type");
>-    };
>+    }
> 
>     function primitive_type() {
>       const num_type = integer_type() || float_type();
>       if (num_type) return num_type;
>-      all_ws();
>-      if (consume(ID, "boolean")) return "boolean";
>-      if (consume(ID, "byte")) return "byte";
>-      if (consume(ID, "octet")) return "octet";
>-    };
>+      if (consume("boolean")) return "boolean";
>+      if (consume("byte")) return "byte";
>+      if (consume("octet")) return "octet";
>+    }
> 
>     function const_value() {
>-      if (consume(ID, "true")) return { type: "boolean", value: true };
>-      if (consume(ID, "false")) return { type: "boolean", value: false };
>-      if (consume(ID, "null")) return { type: "null" };
>-      if (consume(ID, "Infinity")) return { type: "Infinity", negative: false };
>-      if (consume(ID, "NaN")) return { type: "NaN" };
>-      const ret = consume(FLOAT) || consume(INT);
>+      if (consume("true")) return { type: "boolean", value: true };
>+      if (consume("false")) return { type: "boolean", value: false };
>+      if (consume("null")) return { type: "null" };
>+      if (consume("Infinity")) return { type: "Infinity", negative: false };
>+      if (consume("-Infinity")) return { type: "Infinity", negative: true };
>+      if (consume("NaN")) return { type: "NaN" };
>+      const ret = consume(FLOAT, INT);
>       if (ret) return { type: "number", value: ret.value };
>-      const tok = consume(OTHER, "-");
>-      if (tok) {
>-        if (consume(ID, "Infinity")) return { type: "Infinity", negative: true };
>-        else tokens.unshift(tok);
>-      }
>-    };
>+    }
> 
>     function type_suffix(obj) {
>-      while (true) {
>-        all_ws();
>-        if (consume(OTHER, "?")) {
>-          if (obj.nullable) error("Can't nullable more than once");
>-          obj.nullable = true;
>-        } else return;
>+      obj.nullable = !!consume("?");
>+      if (probe("?")) error("Can't nullable more than once");
>+    }
>+
>+    function generic_type(typeName) {
>+      const name = consume("FrozenArray", "Promise", "sequence", "record");
>+      if (!name) {
>+        return;
>+      }
>+      const ret = { generic: name.type };
>+      consume("<") || error(`No opening bracket after ${name.type}`);
>+      switch (name.type) {
>+        case "Promise":
>+          if (probe("[")) error("Promise type cannot have extended attribute");
>+          ret.idlType = return_type(typeName);
>+          break;
>+        case "sequence":
>+        case "FrozenArray":
>+          ret.idlType = type_with_extended_attributes(typeName);
>+          break;
>+        case "record":
>+          if (probe("[")) error("Record key cannot have extended attribute");
>+          ret.idlType = [];
>+          const keyType = consume(...stringTypes);
>+          if (!keyType) error(`Record key must be a string type`);
>+          ret.idlType.push(Object.assign({ type: typeName }, EMPTY_IDLTYPE, { idlType: keyType.value }));
>+          consume(",") || error("Missing comma after record key type");
>+          const valueType = type_with_extended_attributes(typeName) || error("Error parsing generic type record");
>+          ret.idlType.push(valueType);
>+          break;
>       }
>-    };
>+      if (!ret.idlType) error(`Error parsing generic type ${name.type}`);
>+      consume(">") || error(`Missing closing bracket after ${name.type}`);
>+      if (name.type === "Promise" && probe("?")) {
>+        error("Promise type cannot be nullable");
>+      }
>+      type_suffix(ret);
>+      return ret;
>+    }
> 
>-    function single_type() {
>+    function single_type(typeName) {
>+      const ret = Object.assign({ type: typeName || null }, EMPTY_IDLTYPE);
>+      const generic = generic_type(typeName);
>+      if (generic) {
>+        return Object.assign(ret, generic);
>+      }
>       const prim = primitive_type();
>-      const ret = { sequence: false, generic: null, nullable: false, union: false };
>       let name;
>-      let value;
>       if (prim) {
>         ret.idlType = prim;
>-      } else if (name = consume(ID)) {
>-        value = name.value;
>-        all_ws();
>-        // Generic types
>-        if (consume(OTHER, "<")) {
>-          // backwards compat
>-          if (value === "sequence") {
>-            ret.sequence = true;
>-          }
>-          ret.generic = value;
>-          const types = [];
>-          do {
>-            all_ws();
>-            types.push(type_with_extended_attributes() || error("Error parsing generic type " + value));
>-            all_ws();
>-          }
>-          while (consume(OTHER, ","));
>-          if (value === "sequence") {
>-            if (types.length !== 1) error("A sequence must have exactly one subtype");
>-          } else if (value === "record") {
>-            if (types.length !== 2) error("A record must have exactly two subtypes");
>-            if (!/^(DOMString|USVString|ByteString)$/.test(types[0].idlType)) {
>-              error("Record key must be DOMString, USVString, or ByteString");
>-            }
>-            if (types[0].extAttrs) error("Record key cannot have extended attribute");
>-          } else if (value === "Promise") {
>-            if (types[0].extAttrs) error("Promise type cannot have extended attribute");
>-          }
>-          ret.idlType = types.length === 1 ? types[0] : types;
>-          all_ws();
>-          if (!consume(OTHER, ">")) error("Unterminated generic type " + value);
>-          type_suffix(ret);
>-          return ret;
>-        } else {
>-          ret.idlType = value;
>-        }
>+      } else if (name = consume(ID, ...stringTypes)) {
>+        ret.idlType = name.value;
>+        if (probe("<")) error(`Unsupported generic type ${name.value}`);
>       } else {
>         return;
>       }
>       type_suffix(ret);
>       if (ret.nullable && ret.idlType === "any") error("Type any cannot be made nullable");
>       return ret;
>-    };
>-
>-    function union_type() {
>-      all_ws();
>-      if (!consume(OTHER, "(")) return;
>-      const ret = { sequence: false, generic: null, nullable: false, union: true, idlType: [] };
>-      const fst = type_with_extended_attributes() || error("Union type with no content");
>-      ret.idlType.push(fst);
>-      while (true) {
>-        all_ws();
>-        if (!consume(ID, "or")) break;
>-        const typ = type_with_extended_attributes() || error("No type after 'or' in union type");
>+    }
>+
>+    function union_type(typeName) {
>+      if (!consume("(")) return;
>+      const ret = Object.assign({ type: typeName || null }, EMPTY_IDLTYPE, { union: true, idlType: [] });
>+      do {
>+        const typ = type_with_extended_attributes() || error("No type after open parenthesis or 'or' in union type");
>         ret.idlType.push(typ);
>+      } while (consume("or"));
>+      if (ret.idlType.length < 2) {
>+        error("At least two types are expected in a union type but found less");
>       }
>-      if (!consume(OTHER, ")")) error("Unterminated union type");
>+      if (!consume(")")) error("Unterminated union type");
>       type_suffix(ret);
>       return ret;
>-    };
>+    }
> 
>-    function type() {
>-      return single_type() || union_type();
>-    };
>+    function type(typeName) {
>+      return single_type(typeName) || union_type(typeName);
>+    }
> 
>-    function type_with_extended_attributes() {
>+    function type_with_extended_attributes(typeName) {
>       const extAttrs = extended_attrs();
>-      const ret = single_type() || union_type();
>+      const ret = single_type(typeName) || union_type(typeName);
>       if (extAttrs.length && ret) ret.extAttrs = extAttrs;
>       return ret;
>-    };
>+    }
> 
>-    function argument(store) {
>-      const ret = { optional: false, variadic: false };
>-      ret.extAttrs = extended_attrs(store);
>-      all_ws(store, "pea");
>-      const opt_token = consume(ID, "optional");
>+    function argument() {
>+      const start_position = consume_position;
>+      const ret = { optional: false, variadic: false, default: null };
>+      ret.extAttrs = extended_attrs();
>+      const opt_token = consume("optional");
>       if (opt_token) {
>         ret.optional = true;
>-        all_ws();
>       }
>-      ret.idlType = type_with_extended_attributes();
>+      ret.idlType = type_with_extended_attributes("argument-type");
>       if (!ret.idlType) {
>-        if (opt_token) tokens.unshift(opt_token);
>+        unconsume(start_position);
>         return;
>       }
>-      const type_token = last_token;
>-      if (!ret.optional) {
>-        all_ws();
>-        if (tokens.length >= 3 &&
>-          tokens[0].type === "other" && tokens[0].value === "." &&
>-          tokens[1].type === "other" && tokens[1].value === "." &&
>-          tokens[2].type === "other" && tokens[2].value === "."
>-        ) {
>-          tokens.shift();
>-          tokens.shift();
>-          tokens.shift();
>-          ret.variadic = true;
>-        }
>+      if (!ret.optional && consume("...")) {
>+        ret.variadic = true;
>       }
>-      all_ws();
>-      const name = consume(ID);
>+      const name = consume(ID, ...argumentNameKeywords);
>       if (!name) {
>-        if (opt_token) tokens.unshift(opt_token);
>-        tokens.unshift(type_token);
>+        unconsume(start_position);
>         return;
>       }
>-      ret.name = name.value;
>+      ret.name = unescape(name.value);
>+      ret.escapedName = name.value;
>       if (ret.optional) {
>-        all_ws();
>-        const dflt = default_();
>-        if (typeof dflt !== "undefined") {
>-          ret["default"] = dflt;
>-        }
>+        ret.default = default_() || null;
>       }
>       return ret;
>-    };
>+    }
> 
>-    function argument_list(store) {
>+    function argument_list() {
>       const ret = [];
>-      const arg = argument(store ? ret : null);
>-      if (!arg) return;
>+      const arg = argument();
>+      if (!arg) return ret;
>       ret.push(arg);
>       while (true) {
>-        all_ws(store ? ret : null);
>-        if (!consume(OTHER, ",")) return ret;
>-        const nxt = argument(store ? ret : null) || error("Trailing comma in arguments list");
>+        if (!consume(",")) return ret;
>+        const nxt = argument() || error("Trailing comma in arguments list");
>         ret.push(nxt);
>       }
>-    };
>+    }
> 
>-    function simple_extended_attr(store) {
>-      all_ws();
>+    function simple_extended_attr() {
>       const name = consume(ID);
>       if (!name) return;
>       const ret = {
>         name: name.value,
>-        "arguments": null,
>+        arguments: null,
>         type: "extended-attribute",
>         rhs: null
>       };
>-      all_ws();
>-      const eq = consume(OTHER, "=");
>+      const eq = consume("=");
>       if (eq) {
>-        all_ws();
>-        ret.rhs = consume(ID) ||
>-          consume(FLOAT) ||
>-          consume(INT) ||
>-          consume(STR);
>-        if (!ret.rhs && consume(OTHER, "(")) {
>+        ret.rhs = consume(ID, FLOAT, INT, STR);
>+        if (ret.rhs) {
>+          // No trivia exposure yet
>+          ret.rhs.trivia = undefined;
>+        }
>+      }
>+      if (consume("(")) {
>+        if (eq && !ret.rhs) {
>           // [Exposed=(Window,Worker)]
>-          const rhs_list = [];
>-          const id = consume(ID);
>-          if (id) {
>-            rhs_list.push(id.value);
>-          }
>-          identifiers(rhs_list);
>-          consume(OTHER, ")") || error("Unexpected token in extended attribute argument list or type pair");
>           ret.rhs = {
>             type: "identifier-list",
>-            value: rhs_list
>+            value: identifiers()
>           };
>         }
>-        if (!ret.rhs) return error("No right hand side to extended attribute assignment");
>-      }
>-      all_ws();
>-      if (consume(OTHER, "(")) {
>-        let args, pair;
>-        // [Constructor(DOMString str)]
>-        if (args = argument_list(store)) {
>-          ret["arguments"] = args;
>-        }
>-        // [Constructor()]
>         else {
>-          ret["arguments"] = [];
>+          // [NamedConstructor=Audio(DOMString src)] or [Constructor(DOMString str)]
>+          ret.arguments = argument_list();
>         }
>-        all_ws();
>-        consume(OTHER, ")") || error("Unexpected token in extended attribute argument list");
>+        consume(")") || error("Unexpected token in extended attribute argument list");
>       }
>+      if (eq && !ret.rhs) error("No right hand side to extended attribute assignment");
>       return ret;
>-    };
>+    }
> 
>     // Note: we parse something simpler than the official syntax. It's all that ever
>     // seems to be used
>-    function extended_attrs(store) {
>+    function extended_attrs() {
>       const eas = [];
>-      all_ws(store);
>-      if (!consume(OTHER, "[")) return eas;
>-      eas[0] = simple_extended_attr(store) || error("Extended attribute with not content");
>-      all_ws();
>-      while (consume(OTHER, ",")) {
>-        if (eas.length) {
>-          eas.push(simple_extended_attr(store));
>-        } else {
>-          eas.push(simple_extended_attr(store) || error("Trailing comma in extended attribute"));
>-        }
>+      if (!consume("[")) return eas;
>+      eas[0] = simple_extended_attr() || error("Extended attribute with not content");
>+      while (consume(",")) {
>+        eas.push(simple_extended_attr() || error("Trailing comma in extended attribute"));
>       }
>-      all_ws();
>-      consume(OTHER, "]") || error("No end of extended attribute");
>+      consume("]") || error("No end of extended attribute");
>       return eas;
>-    };
>+    }
> 
>     function default_() {
>-      all_ws();
>-      if (consume(OTHER, "=")) {
>-        all_ws();
>+      if (consume("=")) {
>         const def = const_value();
>         if (def) {
>           return def;
>-        } else if (consume(OTHER, "[")) {
>-          if (!consume(OTHER, "]")) error("Default sequence value must be empty");
>+        } else if (consume("[")) {
>+          if (!consume("]")) error("Default sequence value must be empty");
>           return { type: "sequence", value: [] };
>         } else {
>           const str = consume(STR) || error("No value for default");
>-          str.value = str.value.replace(/^"/, "").replace(/"$/, "");
>+          str.value = str.value.slice(1, -1);
>+          // No trivia exposure yet
>+          str.trivia = undefined;
>           return str;
>         }
>       }
>-    };
>+    }
> 
>-    function const_(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "const")) return;
>+    function const_() {
>+      if (!consume("const")) return;
>       const ret = { type: "const", nullable: false };
>-      all_ws();
>       let typ = primitive_type();
>       if (!typ) {
>         typ = consume(ID) || error("No type for const");
>         typ = typ.value;
>       }
>-      ret.idlType = typ;
>-      all_ws();
>-      if (consume(OTHER, "?")) {
>-        ret.nullable = true;
>-        all_ws();
>-      }
>+      ret.idlType = Object.assign({ type: "const-type" }, EMPTY_IDLTYPE, { idlType: typ });
>+      type_suffix(ret);
>       const name = consume(ID) || error("No name for const");
>       ret.name = name.value;
>-      all_ws();
>-      consume(OTHER, "=") || error("No value assignment for const");
>-      all_ws();
>+      consume("=") || error("No value assignment for const");
>       const cnt = const_value();
>       if (cnt) ret.value = cnt;
>       else error("No value for const");
>-      all_ws();
>-      consume(OTHER, ";") || error("Unterminated const");
>+      consume(";") || error("Unterminated const");
>       return ret;
>-    };
>+    }
> 
>     function inheritance() {
>-      all_ws();
>-      if (consume(OTHER, ":")) {
>-        all_ws();
>+      if (consume(":")) {
>         const inh = consume(ID) || error("No type in inheritance");
>         return inh.value;
>       }
>-    };
>+    }
> 
>-    function operation_rest(ret, store) {
>-      all_ws();
>+    function operation_rest(ret) {
>       if (!ret) ret = {};
>       const name = consume(ID);
>-      ret.name = name ? name.value : null;
>-      all_ws();
>-      consume(OTHER, "(") || error("Invalid operation");
>-      ret["arguments"] = argument_list(store) || [];
>-      all_ws();
>-      consume(OTHER, ")") || error("Unterminated operation");
>-      all_ws();
>-      consume(OTHER, ";") || error("Unterminated operation");
>+      ret.name = name ? unescape(name.value) : null;
>+      ret.escapedName = name ? name.value : null;
>+      consume("(") || error("Invalid operation");
>+      ret.arguments = argument_list();
>+      consume(")") || error("Unterminated operation");
>+      consume(";") || error("Unterminated operation");
>       return ret;
>-    };
>+    }
> 
>-    function callback(store) {
>-      all_ws(store, "pea");
>+    function callback() {
>       let ret;
>-      if (!consume(ID, "callback")) return;
>-      all_ws();
>-      const tok = consume(ID, "interface");
>+      if (!consume("callback")) return;
>+      const tok = consume("interface");
>       if (tok) {
>-        ret = interface_rest();
>-        ret.type = "callback interface";
>+        ret = interface_rest(false, "callback interface");
>         return ret;
>       }
>       const name = consume(ID) || error("No name for callback");
>-      ret = { type: "callback", name: sanitize_name(name.value, "callback") };
>-      all_ws();
>-      consume(OTHER, "=") || error("No assignment in callback");
>-      all_ws();
>-      ret.idlType = return_type();
>-      all_ws();
>-      consume(OTHER, "(") || error("No arguments in callback");
>-      ret["arguments"] = argument_list(store) || [];
>-      all_ws();
>-      consume(OTHER, ")") || error("Unterminated callback");
>-      all_ws();
>-      consume(OTHER, ";") || error("Unterminated callback");
>+      ret = current = { type: "callback", name: sanitize_name(name.value, "callback") };
>+      consume("=") || error("No assignment in callback");
>+      ret.idlType = return_type() || error("Missing return type");
>+      consume("(") || error("No arguments in callback");
>+      ret.arguments = argument_list();
>+      consume(")") || error("Unterminated callback");
>+      consume(";") || error("Unterminated callback");
>       return ret;
>-    };
>+    }
> 
>-    function attribute(store) {
>-      all_ws(store, "pea");
>-      const grabbed = [];
>+    function attribute({ noInherit = false, readonly = false } = {}) {
>+      const start_position = consume_position;
>       const ret = {
>         type: "attribute",
>-        "static": false,
>+        static: false,
>         stringifier: false,
>         inherit: false,
>         readonly: false
>       };
>-      const w = all_ws();
>-      if (w) grabbed.push(w);
>-      if (consume(ID, "inherit")) {
>-        if (ret["static"] || ret.stringifier) error("Cannot have a static or stringifier inherit");
>+      if (!noInherit && consume("inherit")) {
>         ret.inherit = true;
>-        grabbed.push(last_token);
>-        const w = all_ws();
>-        if (w) grabbed.push(w);
>       }
>-      if (consume(ID, "readonly")) {
>+      if (consume("readonly")) {
>         ret.readonly = true;
>-        grabbed.push(last_token);
>-        const w = all_ws();
>-        if (w) grabbed.push(w);
>+      } else if (readonly && probe("attribute")) {
>+        error("Attributes must be readonly in this context");
>       }
>       const rest = attribute_rest(ret);
>       if (!rest) {
>-        tokens = grabbed.concat(tokens);
>+        unconsume(start_position);
>       }
>       return rest;
>-    };
>+    }
> 
>     function attribute_rest(ret) {
>-      if (!consume(ID, "attribute")) {
>+      if (!consume("attribute")) {
>         return;
>       }
>-      all_ws();
>-      ret.idlType = type_with_extended_attributes() || error("No type in attribute");
>-      if (ret.idlType.sequence) error("Attributes cannot accept sequence types");
>+      ret.idlType = type_with_extended_attributes("attribute-type") || error("No type in attribute");
>+      if (ret.idlType.generic === "sequence") error("Attributes cannot accept sequence types");
>       if (ret.idlType.generic === "record") error("Attributes cannot accept record types");
>-      all_ws();
>-      const name = consume(ID) || error("No name in attribute");
>-      ret.name = name.value;
>-      all_ws();
>-      consume(OTHER, ";") || error("Unterminated attribute");
>+      const name = consume(ID, "required") || error("No name in attribute");
>+      ret.name = unescape(name.value);
>+      ret.escapedName = name.value;
>+      consume(";") || error("Unterminated attribute");
>       return ret;
>-    };
>+    }
> 
>-    function return_type() {
>-      const typ = type();
>-      if (!typ) {
>-        if (consume(ID, "void")) {
>-          return "void";
>-        } else error("No return type");
>+    function return_type(typeName) {
>+      const typ = type(typeName || "return-type");
>+      if (typ) {
>+        return typ;
>+      }
>+      if (consume("void")) {
>+        return Object.assign({ type: "return-type" }, EMPTY_IDLTYPE, { idlType: "void" });
>       }
>-      return typ;
>-    };
>+    }
> 
>-    function operation(store) {
>-      all_ws(store, "pea");
>+    function operation({ regular = false } = {}) {
>       const ret = Object.assign({}, EMPTY_OPERATION);
>-      while (true) {
>-        all_ws();
>-        if (consume(ID, "getter")) ret.getter = true;
>-        else if (consume(ID, "setter")) ret.setter = true;
>-        else if (consume(ID, "deleter")) ret.deleter = true;
>+      while (!regular) {
>+        if (consume("getter")) ret.getter = true;
>+        else if (consume("setter")) ret.setter = true;
>+        else if (consume("deleter")) ret.deleter = true;
>         else break;
>       }
>-      if (ret.getter || ret.setter || ret.deleter) {
>-        all_ws();
>-        ret.idlType = return_type();
>-        operation_rest(ret, store);
>-        return ret;
>-      }
>-      ret.idlType = return_type();
>-      all_ws();
>-      if (consume(ID, "iterator")) {
>-        all_ws();
>-        ret.type = "iterator";
>-        if (consume(ID, "object")) {
>-          ret.iteratorObject = "object";
>-        } else if (consume(OTHER, "=")) {
>-          all_ws();
>-          var name = consume(ID) || error("No right hand side in iterator");
>-          ret.iteratorObject = name.value;
>-        }
>-        all_ws();
>-        consume(OTHER, ";") || error("Unterminated iterator");
>-        return ret;
>-      } else {
>-        operation_rest(ret, store);
>-        return ret;
>-      }
>-    };
>-
>-    function static_member(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "static")) return;
>-      all_ws();
>-      return noninherited_attribute(store, "static") ||
>-        regular_operation(store, "static") ||
>+      ret.idlType = return_type() || error("Missing return type");
>+      operation_rest(ret);
>+      return ret;
>+    }
>+
>+    function static_member() {
>+      if (!consume("static")) return;
>+      const member = attribute({ noInherit: true }) ||
>+        operation({ regular: true }) ||
>         error("No body in static member");
>+      member.static = true;
>+      return member;
>     }
> 
>-    function stringifier(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "stringifier")) return;
>-      all_ws();
>-      if (consume(OTHER, ";")) {
>+    function stringifier() {
>+      if (!consume("stringifier")) return;
>+      if (consume(";")) {
>         return Object.assign({}, EMPTY_OPERATION, { stringifier: true });
>       }
>-      return noninherited_attribute(store, "stringifier") ||
>-        regular_operation(store, "stringifier") ||
>+      const member = attribute({ noInherit: true }) ||
>+        operation({ regular: true }) ||
>         error("Unterminated stringifier");
>+      member.stringifier = true;
>+      return member;
>     }
> 
>-    function identifiers(arr) {
>+    function identifiers() {
>+      const arr = [];
>+      const id = consume(ID);
>+      if (id) {
>+        arr.push(id.value);
>+      }
>+      else error("Expected identifiers but not found");
>       while (true) {
>-        all_ws();
>-        if (consume(OTHER, ",")) {
>-          all_ws();
>+        if (consume(",")) {
>           const name = consume(ID) || error("Trailing comma in identifiers list");
>           arr.push(name.value);
>         } else break;
>       }
>-    };
>+      return arr;
>+    }
> 
>     function iterable_type() {
>-      if (consume(ID, "iterable")) return "iterable";
>-      else if (consume(ID, "legacyiterable")) return "legacyiterable";
>-      else if (consume(ID, "maplike")) return "maplike";
>-      else if (consume(ID, "setlike")) return "setlike";
>+      if (consume("iterable")) return "iterable";
>+      else if (consume("legacyiterable")) return "legacyiterable";
>+      else if (consume("maplike")) return "maplike";
>+      else if (consume("setlike")) return "setlike";
>       else return;
>-    };
>+    }
> 
>     function readonly_iterable_type() {
>-      if (consume(ID, "maplike")) return "maplike";
>-      else if (consume(ID, "setlike")) return "setlike";
>+      if (consume("maplike")) return "maplike";
>+      else if (consume("setlike")) return "setlike";
>       else return;
>-    };
>+    }
> 
>-    function iterable(store) {
>-      all_ws(store, "pea");
>-      const grabbed = [];
>+    function iterable() {
>+      const start_position = consume_position;
>       const ret = { type: null, idlType: null, readonly: false };
>-      if (consume(ID, "readonly")) {
>+      if (consume("readonly")) {
>         ret.readonly = true;
>-        grabbed.push(last_token);
>-        var w = all_ws();
>-        if (w) grabbed.push(w);
>       }
>       const consumeItType = ret.readonly ? readonly_iterable_type : iterable_type;
> 
>       const ittype = consumeItType();
>       if (!ittype) {
>-        tokens = grabbed.concat(tokens);
>+        unconsume(start_position);
>         return;
>       }
> 
>@@ -670,357 +690,255 @@
>       ret.type = ittype;
>       if (ret.type !== 'maplike' && ret.type !== 'setlike')
>         delete ret.readonly;
>-      all_ws();
>-      if (consume(OTHER, "<")) {
>-        ret.idlType = type_with_extended_attributes() || error(`Error parsing ${ittype} declaration`);
>-        all_ws();
>+      if (consume("<")) {
>+        ret.idlType = [type_with_extended_attributes()] || error(`Error parsing ${ittype} declaration`);
>         if (secondTypeAllowed) {
>-          let type2 = null;
>-          if (consume(OTHER, ",")) {
>-            all_ws();
>-            type2 = type_with_extended_attributes();
>-            all_ws();
>+          if (consume(",")) {
>+            ret.idlType.push(type_with_extended_attributes());
>           }
>-          if (type2)
>-            ret.idlType = [ret.idlType, type2];
>           else if (secondTypeRequired)
>             error(`Missing second type argument in ${ittype} declaration`);
>         }
>-        if (!consume(OTHER, ">")) error(`Unterminated ${ittype} declaration`);
>-        all_ws();
>-        if (!consume(OTHER, ";")) error(`Missing semicolon after ${ittype} declaration`);
>+        if (!consume(">")) error(`Unterminated ${ittype} declaration`);
>+        if (!consume(";")) error(`Missing semicolon after ${ittype} declaration`);
>       } else
>         error(`Error parsing ${ittype} declaration`);
> 
>       return ret;
>-    };
>+    }
> 
>-    function interface_rest(isPartial, store) {
>-      all_ws();
>+    function interface_rest(isPartial, typeName = "interface") {
>       const name = consume(ID) || error("No name for interface");
>       const mems = [];
>-      const ret = {
>-        type: "interface",
>+      const ret = current = {
>+        type: typeName,
>         name: isPartial ? name.value : sanitize_name(name.value, "interface"),
>-        partial: false,
>+        partial: isPartial,
>         members: mems
>       };
>       if (!isPartial) ret.inheritance = inheritance() || null;
>-      all_ws();
>-      consume(OTHER, "{") || error("Bodyless interface");
>+      consume("{") || error("Bodyless interface");
>       while (true) {
>-        all_ws(store ? mems : null);
>-        if (consume(OTHER, "}")) {
>-          all_ws();
>-          consume(OTHER, ";") || error("Missing semicolon after interface");
>+        if (consume("}")) {
>+          consume(";") || error("Missing semicolon after interface");
>           return ret;
>         }
>-        const ea = extended_attrs(store ? mems : null);
>-        all_ws();
>-        const cnt = const_(store ? mems : null);
>-        if (cnt) {
>-          cnt.extAttrs = ea;
>-          ret.members.push(cnt);
>-          continue;
>-        }
>-        const mem = (opt.allowNestedTypedefs && typedef(store ? mems : null)) ||
>-          static_member(store ? mems : null) ||
>-          stringifier(store ? mems : null) ||
>-          iterable(store ? mems : null) ||
>-          attribute(store ? mems : null) ||
>-          operation(store ? mems : null) ||
>+        const ea = extended_attrs();
>+        const mem = const_() ||
>+          static_member() ||
>+          stringifier() ||
>+          iterable() ||
>+          attribute() ||
>+          operation() ||
>           error("Unknown member");
>         mem.extAttrs = ea;
>         ret.members.push(mem);
>       }
>-    };
>+    }
> 
>-    function mixin_rest(isPartial, store) {
>-      all_ws();
>-      if (!consume(ID, "mixin")) return;
>-      all_ws();
>+    function mixin_rest(isPartial) {
>+      if (!consume("mixin")) return;
>       const name = consume(ID) || error("No name for interface mixin");
>       const mems = [];
>-      const ret = {
>+      const ret = current = {
>         type: "interface mixin",
>         name: isPartial ? name.value : sanitize_name(name.value, "interface mixin"),
>-        partial: false,
>+        partial: isPartial,
>         members: mems
>       };
>-      all_ws();
>-      consume(OTHER, "{") || error("Bodyless interface mixin");
>+      consume("{") || error("Bodyless interface mixin");
>       while (true) {
>-        all_ws(store ? mems : null);
>-        if (consume(OTHER, "}")) {
>-          all_ws();
>-          consume(OTHER, ";") || error("Missing semicolon after interface mixin");
>+        if (consume("}")) {
>+          consume(";") || error("Missing semicolon after interface mixin");
>           return ret;
>         }
>-        const ea = extended_attrs(store ? mems : null);
>-        all_ws();
>-        const cnt = const_(store ? mems : null);
>-        if (cnt) {
>-          cnt.extAttrs = ea;
>-          ret.members.push(cnt);
>-          continue;
>-        }
>-        const mem = stringifier(store ? mems : null) ||
>-          noninherited_attribute(store ? mems : null) ||
>-          regular_operation(store ? mems : null) ||
>+        const ea = extended_attrs();
>+        const mem = const_() ||
>+          stringifier() ||
>+          attribute({ noInherit: true }) ||
>+          operation({ regular: true }) ||
>           error("Unknown member");
>         mem.extAttrs = ea;
>         ret.members.push(mem);
>       }
>     }
> 
>-    function interface_(isPartial, store) {
>-      all_ws(isPartial ? null : store, "pea");
>-      if (!consume(ID, "interface")) return;
>-      return mixin_rest(isPartial, store) ||
>-        interface_rest(isPartial, store) ||
>+    function interface_(isPartial) {
>+      if (!consume("interface")) return;
>+      return mixin_rest(isPartial) ||
>+        interface_rest(isPartial) ||
>         error("Interface has no proper body");
>     }
> 
>-    function namespace(isPartial, store) {
>-      all_ws(isPartial ? null : store, "pea");
>-      if (!consume(ID, "namespace")) return;
>-      all_ws();
>+    function namespace(isPartial) {
>+      if (!consume("namespace")) return;
>       const name = consume(ID) || error("No name for namespace");
>       const mems = [];
>-      const ret = {
>+      const ret = current = {
>         type: "namespace",
>         name: isPartial ? name.value : sanitize_name(name.value, "namespace"),
>         partial: isPartial,
>         members: mems
>       };
>-      all_ws();
>-      consume(OTHER, "{") || error("Bodyless namespace");
>+      consume("{") || error("Bodyless namespace");
>       while (true) {
>-        all_ws(store ? mems : null);
>-        if (consume(OTHER, "}")) {
>-          all_ws();
>-          consume(OTHER, ";") || error("Missing semicolon after namespace");
>+        if (consume("}")) {
>+          consume(";") || error("Missing semicolon after namespace");
>           return ret;
>         }
>-        const ea = extended_attrs(store ? mems : null);
>-        all_ws();
>-        const mem = noninherited_attribute(store ? mems : null) ||
>-          regular_operation(store ? mems : null) ||
>+        const ea = extended_attrs();
>+        const mem = attribute({ noInherit: true, readonly: true }) ||
>+          operation({ regular: true }) ||
>           error("Unknown member");
>         mem.extAttrs = ea;
>         ret.members.push(mem);
>       }
>     }
> 
>-    function noninherited_attribute(store, prefix) {
>-      const w = all_ws(store, "pea");
>-      const grabbed = [];
>-      const ret = {
>-        type: "attribute",
>-        "static": false,
>-        stringifier: false,
>-        inherit: false,
>-        readonly: false
>-      };
>-      if (prefix) {
>-        ret[prefix] = true;
>-      }
>-      if (w) grabbed.push(w);
>-      if (consume(ID, "readonly")) {
>-        ret.readonly = true;
>-        grabbed.push(last_token);
>-        const w = all_ws();
>-        if (w) grabbed.push(w);
>-      }
>-      const rest = attribute_rest(ret);
>-      if (!rest) {
>-        tokens = grabbed.concat(tokens);
>-      }
>-      return rest;
>-    }
>-
>-    function regular_operation(store, prefix) {
>-      all_ws(store, "pea");
>-      const ret = Object.assign({}, EMPTY_OPERATION);
>-      if (prefix) {
>-        ret[prefix] = true;
>-      }
>-      ret.idlType = return_type();
>-      return operation_rest(ret, store);
>-    }
>-
>-    function partial(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "partial")) return;
>-      const thing = dictionary(true, store) ||
>-        interface_(true, store) ||
>-        namespace(true, store) ||
>+    function partial() {
>+      if (!consume("partial")) return;
>+      const thing = dictionary(true) ||
>+        interface_(true) ||
>+        namespace(true) ||
>         error("Partial doesn't apply to anything");
>-      thing.partial = true;
>       return thing;
>-    };
>+    }
> 
>-    function dictionary(isPartial, store) {
>-      all_ws(isPartial ? null : store, "pea");
>-      if (!consume(ID, "dictionary")) return;
>-      all_ws();
>+    function dictionary(isPartial) {
>+      if (!consume("dictionary")) return;
>       const name = consume(ID) || error("No name for dictionary");
>       const mems = [];
>-      const ret = {
>+      const ret = current = {
>         type: "dictionary",
>         name: isPartial ? name.value : sanitize_name(name.value, "dictionary"),
>-        partial: false,
>+        partial: isPartial,
>         members: mems
>       };
>       if (!isPartial) ret.inheritance = inheritance() || null;
>-      all_ws();
>-      consume(OTHER, "{") || error("Bodyless dictionary");
>+      consume("{") || error("Bodyless dictionary");
>       while (true) {
>-        all_ws(store ? mems : null);
>-        if (consume(OTHER, "}")) {
>-          all_ws();
>-          consume(OTHER, ";") || error("Missing semicolon after dictionary");
>+        if (consume("}")) {
>+          consume(";") || error("Missing semicolon after dictionary");
>           return ret;
>         }
>-        const ea = extended_attrs(store ? mems : null);
>-        all_ws(store ? mems : null, "pea");
>-        const required = consume(ID, "required");
>-        const typ = type_with_extended_attributes() || error("No type for dictionary member");
>-        all_ws();
>+        const ea = extended_attrs();
>+        const required = consume("required");
>+        const typ = type_with_extended_attributes("dictionary-type") || error("No type for dictionary member");
>         const name = consume(ID) || error("No name for dictionary member");
>-        const dflt = default_();
>+        const dflt = default_() || null;
>         if (required && dflt) error("Required member must not have a default");
>         const member = {
>           type: "field",
>-          name: name.value,
>+          name: unescape(name.value),
>+          escapedName: name.value,
>           required: !!required,
>           idlType: typ,
>-          extAttrs: ea
>+          extAttrs: ea,
>+          default: dflt
>         };
>-        if (typeof dflt !== "undefined") {
>-          member["default"] = dflt;
>-        }
>         ret.members.push(member);
>-        all_ws();
>-        consume(OTHER, ";") || error("Unterminated dictionary member");
>+        consume(";") || error("Unterminated dictionary member");
>       }
>-    };
>+    }
> 
>-    function enum_(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "enum")) return;
>-      all_ws();
>+    function enum_() {
>+      if (!consume("enum")) return;
>       const name = consume(ID) || error("No name for enum");
>       const vals = [];
>-      const ret = {
>+      const ret = current = {
>         type: "enum",
>         name: sanitize_name(name.value, "enum"),
>         values: vals
>       };
>-      all_ws();
>-      consume(OTHER, "{") || error("No curly for enum");
>-      let saw_comma = false;
>+      consume("{") || error("No curly for enum");
>+      let value_expected = true;
>       while (true) {
>-        all_ws(store ? vals : null);
>-        if (consume(OTHER, "}")) {
>-          all_ws();
>-          consume(OTHER, ";") || error("No semicolon after enum");
>+        if (consume("}")) {
>+          if (!ret.values.length) error("No value in enum");
>+          consume(";") || error("No semicolon after enum");
>           return ret;
>         }
>+        else if (!value_expected) {
>+          error("No comma between enum values");
>+        }
>         const val = consume(STR) || error("Unexpected value in enum");
>-        val.value = val.value.replace(/"/g, "");
>+        val.value = val.value.slice(1, -1);
>+        // No trivia exposure yet
>+        val.trivia = undefined;
>         ret.values.push(val);
>-        all_ws(store ? vals : null);
>-        if (consume(OTHER, ",")) {
>-          if (store) vals.push({ type: "," });
>-          all_ws(store ? vals : null);
>-          saw_comma = true;
>-        } else {
>-          saw_comma = false;
>-        }
>+        value_expected = !!consume(",");
>       }
>-    };
>+    }
> 
>-    function typedef(store) {
>-      all_ws(store, "pea");
>-      if (!consume(ID, "typedef")) return;
>+    function typedef() {
>+      if (!consume("typedef")) return;
>       const ret = {
>         type: "typedef"
>       };
>-      all_ws();
>-      ret.idlType = type_with_extended_attributes() || error("No type in typedef");
>-      all_ws();
>+      ret.idlType = type_with_extended_attributes("typedef-type") || error("No type in typedef");
>       const name = consume(ID) || error("No name in typedef");
>       ret.name = sanitize_name(name.value, "typedef");
>-      all_ws();
>-      consume(OTHER, ";") || error("Unterminated typedef");
>+      current = ret;
>+      consume(";") || error("Unterminated typedef");
>       return ret;
>-    };
>+    }
> 
>-    function implements_(store) {
>-      all_ws(store, "pea");
>+    function implements_() {
>+      const start_position = consume_position;
>       const target = consume(ID);
>       if (!target) return;
>-      const w = all_ws();
>-      if (consume(ID, "implements")) {
>+      if (consume("implements")) {
>         const ret = {
>           type: "implements",
>           target: target.value
>         };
>-        all_ws();
>         const imp = consume(ID) || error("Incomplete implements statement");
>-        ret["implements"] = imp.value;
>-        all_ws();
>-        consume(OTHER, ";") || error("No terminating ; for implements statement");
>+        ret.implements = imp.value;
>+        consume(";") || error("No terminating ; for implements statement");
>         return ret;
>       } else {
>         // rollback
>-        tokens.unshift(w);
>-        tokens.unshift(target);
>+        unconsume(start_position);
>       }
>-    };
>+    }
> 
>-    function includes(store) {
>-      all_ws(store, "pea");
>+    function includes() {
>+      const start_position = consume_position;
>       const target = consume(ID);
>       if (!target) return;
>-      const w = all_ws();
>-      if (consume(ID, "includes")) {
>+      if (consume("includes")) {
>         const ret = {
>           type: "includes",
>           target: target.value
>         };
>-        all_ws();
>         const imp = consume(ID) || error("Incomplete includes statement");
>-        ret["includes"] = imp.value;
>-        all_ws();
>-        consume(OTHER, ";") || error("No terminating ; for includes statement");
>+        ret.includes = imp.value;
>+        consume(";") || error("No terminating ; for includes statement");
>         return ret;
>       } else {
>         // rollback
>-        tokens.unshift(w);
>-        tokens.unshift(target);
>+        unconsume(start_position);
>       }
>-    };
>-
>-    function definition(store) {
>-      return callback(store) ||
>-        interface_(false, store) ||
>-        partial(store) ||
>-        dictionary(false, store) ||
>-        enum_(store) ||
>-        typedef(store) ||
>-        implements_(store) ||
>-        includes(store) ||
>-        namespace(false, store);
>-    };
>-
>-    function definitions(store) {
>+    }
>+
>+    function definition() {
>+      return callback() ||
>+        interface_(false) ||
>+        partial() ||
>+        dictionary(false) ||
>+        enum_() ||
>+        typedef() ||
>+        implements_() ||
>+        includes() ||
>+        namespace(false);
>+    }
>+
>+    function definitions() {
>       if (!tokens.length) return [];
>       const defs = [];
>       while (true) {
>-        const ea = extended_attrs(store ? defs : null);
>-        const def = definition(store ? defs : null);
>+        const ea = extended_attrs();
>+        const def = definition();
>         if (!def) {
>           if (ea.length) error("Stray extended attributes");
>           break;
>@@ -1029,17 +947,16 @@
>         defs.push(def);
>       }
>       return defs;
>-    };
>-    const res = definitions(opt.ws);
>-    if (tokens.length) error("Unrecognised tokens");
>+    }
>+    const res = definitions();
>+    if (consume_position < tokens.length) error("Unrecognised tokens");
>     return res;
>-  };
>+  }
> 
>   const obj = {
>-    parse(str, opt) {
>-      if (!opt) opt = {};
>+    parse(str) {
>       const tokens = tokenise(str);
>-      return parse(tokens, opt);
>+      return parse(tokens);
>     }
>   };
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/writer.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/writer.js
>index f7c79f8289358a5ba57911246440fb192f099e08..b3097a6f8a74e4cdeaf71f688ece20423c238a0d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/writer.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/lib/writer.js
>@@ -1,280 +1,221 @@
>-(function() {
>+"use strict";
> 
>-  var write = function(ast, opt) {
>-    var curPea = "",
>-      curTPea = "",
>-      opt = opt || {},
>-      noop = function(str) {
>-        return str; },
>-      optNames = "type".split(" "),
>-      context = [];
>-    for (var i = 0, n = optNames.length; i < n; i++) {
>-      var o = optNames[i];
>+(() => {
>+  function write(ast, opt = {}) {
>+    const noop = str => str;
>+    const optNames = "type".split(" ");
>+    const context = [];
>+    for (const o of optNames) {
>       if (!opt[o]) opt[o] = noop;
>     }
> 
>-    var literal = function(it) {
>+    function literal(it) {
>       return it.value;
>     };
>-    var wsPea = function(it) {
>-      curPea += it.value;
>-      return "";
>-    };
>-    var wsTPea = function(it) {
>-      curTPea += it.value;
>-      return "";
>-    };
>-    var lineComment = function(it) {
>-      return "//" + it.value + "\n";
>-    };
>-    var multilineComment = function(it) {
>-      return "/*" + it.value + "*/";
>-    };
>-    var type = function(it) {
>+    function type(it) {
>       if (typeof it === "string") return opt.type(it); // XXX should maintain some context
>-      if (it.union) return "(" + it.idlType.map(type).join(" or ") + ")";
>-      var ret = "";
>-      if (it.generic) ret += it.generic + "<";
>-      else if (it.sequence) ret += "sequence<";
>-      if (Array.isArray(it.idlType)) ret += it.idlType.map(type).join(", ");
>-      else ret += type(it.idlType);
>-      if (it.array || it.generic === 'Array') {
>-        for (var i = 0, n = it.nullableArray.length; i < n; i++) {
>-          var val = it.nullableArray[i];
>-          if (val) ret += "?";
>-          ret += "[]";
>-        }
>+      let ret = extended_attributes(it.extAttrs);
>+      if (it.union) ret += `(${it.idlType.map(type).join(" or ")})`;
>+      else {
>+        if (it.generic) ret += `${it.generic}<`;
>+        if (Array.isArray(it.idlType)) ret += it.idlType.map(type).join(", ");
>+        else ret += type(it.idlType);
>+        if (it.generic) ret += ">";
>       }
>-      if (it.generic || it.sequence) ret += ">";
>       if (it.nullable) ret += "?";
> 
>       return ret;
>     };
>-    var const_value = function(it) {
>-      var tp = it.type;
>+    function const_value(it) {
>+      const tp = it.type;
>       if (tp === "boolean") return it.value ? "true" : "false";
>       else if (tp === "null") return "null";
>       else if (tp === "Infinity") return (it.negative ? "-" : "") + "Infinity";
>       else if (tp === "NaN") return "NaN";
>       else if (tp === "number") return it.value;
>-      else return '"' + it.value + '"';
>+      else if (tp === "sequence") return "[]";
>+      else return `"${it.value}"`;
>     };
>-    var argument = function(arg, pea) {
>-      var ret = extended_attributes(arg.extAttrs, pea);
>+    function argument(arg) {
>+      let ret = extended_attributes(arg.extAttrs);
>       if (arg.optional) ret += "optional ";
>       ret += type(arg.idlType);
>       if (arg.variadic) ret += "...";
>-      ret += " " + arg.name;
>-      if (arg["default"]) ret += " = " + const_value(arg["default"]);
>+      ret += ` ${arg.escapedName}`;
>+      if (arg.default) ret += ` = ${const_value(arg.default)}`;
>       return ret;
>     };
>-    var args = function(its) {
>-      var res = "",
>-        pea = "";
>-      for (var i = 0, n = its.length; i < n; i++) {
>-        var arg = its[i];
>-        if (arg.type === "ws") res += arg.value;
>-        else if (arg.type === "ws-pea") pea += arg.value;
>-        else {
>-          res += argument(arg, pea);
>-          if (i < n - 1) res += ",";
>-          pea = "";
>-        }
>-      }
>-      return res;
>-    };
>-    var make_ext_at = function(it) {
>-      if (it["arguments"] === null) return it.name;
>+    function make_ext_at(it) {
>       context.unshift(it);
>-      var ret = it.name + "(" + (it["arguments"].length ? args(it["arguments"]) : "") + ")";
>+      let ret = it.name;
>+      if (it.rhs) {
>+        if (it.rhs.type === "identifier-list") ret += `=(${it.rhs.value.join(",")})`;
>+        else ret += `=${it.rhs.value}`;
>+      }
>+      if (it.arguments) ret += `(${it.arguments.length ? it.arguments.map(argument).join(",") : ""})`;
>       context.shift(); // XXX need to add more contexts, but not more than needed for ReSpec
>       return ret;
>     };
>-    var extended_attributes = function(eats, pea) {
>+    function extended_attributes(eats) {
>       if (!eats || !eats.length) return "";
>-      return "[" + eats.map(make_ext_at).join(", ") + "]" + pea;
>+      return `[${eats.map(make_ext_at).join(", ")}]`;
>     };
> 
>-    var modifiers = "getter setter creator deleter legacycaller stringifier static".split(" ");
>-    var operation = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>+    const modifiers = "getter setter deleter stringifier static".split(" ");
>+    function operation(it) {
>+      let ret = extended_attributes(it.extAttrs);
>       if (it.stringifier && !it.idlType) return "stringifier;";
>-      for (var i = 0, n = modifiers.length; i < n; i++) {
>-        var mod = modifiers[i];
>+      for (const mod of modifiers) {
>         if (it[mod]) ret += mod + " ";
>       }
>       ret += type(it.idlType) + " ";
>-      if (it.name) ret += it.name;
>-      ret += "(" + args(it["arguments"]) + ");";
>+      if (it.name) ret += it.escapedName;
>+      ret += `(${it.arguments.map(argument).join(",")});`;
>       return ret;
>     };
> 
>-    var attribute = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      if (it["static"]) ret += "static ";
>+    function attribute(it) {
>+      let ret = extended_attributes(it.extAttrs);
>+      if (it.static) ret += "static ";
>       if (it.stringifier) ret += "stringifier ";
>-      if (it.readonly) ret += "readonly ";
>       if (it.inherit) ret += "inherit ";
>-      ret += "attribute " + type(it.idlType) + " " + it.name + ";";
>+      if (it.readonly) ret += "readonly ";
>+      ret += `attribute ${type(it.idlType)} ${it.escapedName};`;
>       return ret;
>     };
> 
>-    var interface_ = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>+    function interface_(it) {
>+      let ret = extended_attributes(it.extAttrs);
>       if (it.partial) ret += "partial ";
>-      ret += "interface " + it.name + " ";
>-      if (it.inheritance) ret += ": " + it.inheritance + " ";
>-      ret += "{" + iterate(it.members) + "};";
>+      ret += `interface ${it.name} `;
>+      if (it.inheritance) ret += `: ${it.inheritance} `;
>+      ret += `{${iterate(it.members)}};`;
>       return ret;
>     };
> 
>-    var dictionary = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>+    function interface_mixin(it) {
>+      let ret = extended_attributes(it.extAttrs);
>       if (it.partial) ret += "partial ";
>-      ret += "dictionary " + it.name + " ";
>-      ret += "{" + iterate(it.members) + "};";
>+      ret += `interface mixin ${it.name} `;
>+      ret += `{${iterate(it.members)}};`;
>+      return ret;
>+    }
>+
>+    function namespace(it) {
>+      let ret = extended_attributes(it.extAttrs);
>+      if (it.partial) ret += "partial ";
>+      ret += `namespace ${it.name} `;
>+      ret += `{${iterate(it.members)}};`;
>+      return ret;
>+    }
>+
>+    function dictionary(it) {
>+      let ret = extended_attributes(it.extAttrs);
>+      if (it.partial) ret += "partial ";
>+      ret += `dictionary ${it.name} `;
>+      if (it.inheritance) ret += `: ${it.inheritance} `;
>+      ret += `{${iterate(it.members)}};`;
>       return ret;
>     };
>-    var field = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>+    function field(it) {
>+      let ret = extended_attributes(it.extAttrs);
>       if (it.required) ret += "required ";
>-      ret += type(it.idlType) + " " + it.name;
>-      if (it["default"]) ret += " = " + const_value(it["default"]);
>+      ret += `${type(it.idlType)} ${it.escapedName}`;
>+      if (it.default) ret += ` = ${const_value(it.default)}`;
>       ret += ";";
>       return ret;
>     };
>-    var exception = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      ret += "exception " + it.name + " ";
>-      if (it.inheritance) ret += ": " + it.inheritance + " ";
>-      ret += "{" + iterate(it.members) + "};";
>-      return ret;
>+    function const_(it) {
>+      const ret = extended_attributes(it.extAttrs);
>+      return `${ret}const ${type(it.idlType)}${it.nullable ? "?" : ""} ${it.name} = ${const_value(it.value)};`;
>     };
>-    var const_ = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      return ret + "const " + type(it.idlType) + " " + it.name + " = " + const_value(it.value) + ";";
>+    function typedef(it) {
>+      let ret = extended_attributes(it.extAttrs);
>+      ret += `typedef ${extended_attributes(it.typeExtAttrs)}`;
>+      return `${ret}${type(it.idlType)} ${it.name};`;
>     };
>-    var typedef = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      ret += "typedef " + extended_attributes(it.typeExtAttrs, curTPea);
>-      curTPea = "";
>-      return ret + type(it.idlType) + " " + it.name + ";";
>+    function implements_(it) {
>+      const ret = extended_attributes(it.extAttrs);
>+      return `${ret}${it.target} implements ${it.implements};`;
>     };
>-    var implements_ = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      return ret + it.target + " implements " + it["implements"] + ";";
>+    function includes(it) {
>+      const ret = extended_attributes(it.extAttrs);
>+      return `${ret}${it.target} includes ${it.includes};`;
>     };
>-    var callback = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      return ret + "callback " + it.name + " = " + type(it.idlType) +
>-        "(" + args(it["arguments"]) + ");";
>+    function callback(it) {
>+      const ret = extended_attributes(it.extAttrs);
>+      return `${ret}callback ${it.name} = ${type(it.idlType)}(${it.arguments.map(argument).join(",")});`;
>     };
>-    var enum_ = function(it) {
>-      var ret = extended_attributes(it.extAttrs, curPea);
>-      curPea = "";
>-      ret += "enum " + it.name + " {";
>-      for (var i = 0, n = it.values.length; i < n; i++) {
>-        var v = it.values[i];
>-        if (typeof v === "string") ret += '"' + v + '"';
>-        else if (v.type === "ws") ret += v.value;
>-        else if (v.type === ",") ret += ",";
>+    function enum_(it) {
>+      let ret = extended_attributes(it.extAttrs);
>+      ret += `enum ${it.name} {`;
>+      for (const v of it.values) {
>+        ret += `"${v.value}",`;
>       }
>       return ret + "};";
>     };
>-    var serializer = function(it) {
>-      var ret = "serializer";
>-      if (it.name) {
>-        ret += " = " + it.name + ";";
>-      } else if (it.patternList) {
>-        ret += " = [ " + it.names.join(", ") + " ];";
>-      } else if (it.patternMap) {
>-        ret += " = { " + it.names.join(", ") + " };";
>-      } else if (it.operation) {
>-        ret += " " + operation(it);
>-      } else {
>-        ret += ";";
>-      }
>-      return ret;
>-    };
>-    var iterable = function(it) {
>-      return "iterable<" + (it.idlType instanceof Array ? it.idlType.map(type).join(", ") : type(it.idlType)) + ">;";
>+    function iterable(it) {
>+      return `iterable<${Array.isArray(it.idlType) ? it.idlType.map(type).join(", ") : type(it.idlType)}>;`;
>     };
>-    var legacyiterable = function(it) {
>-      return "legacyiterable<" + (it.idlType instanceof Array ? it.idlType.map(type).join(", ") : type(it.idlType)) + ">;";
>+    function legacyiterable(it) {
>+      return `legacyiterable<${Array.isArray(it.idlType) ? it.idlType.map(type).join(", ") : type(it.idlType)}>;`;
>     };
>-    var maplike = function(it) {
>-      return (it.readonly ? "readonly " : "") + "maplike<" +
>-        it.idlType.map(type).join(", ") + ">;";
>+    function maplike(it) {
>+      return `${it.readonly ? "readonly " : ""}maplike<${it.idlType.map(type).join(", ")}>;`;
>     };
>-    var setlike = function(it) {
>-      return (it.readonly ? "readonly " : "") + "setlike<" +
>-        type(it.idlType) + ">;";
>+    function setlike(it) {
>+      return `${it.readonly ? "readonly " : ""}setlike<${type(it.idlType[0])}>;`;
>     };
>-    var callbackInterface = function(it) {
>-      return 'callback ' + interface_(it);
>+    function callbackInterface(it) {
>+      return `callback ${interface_(it)}`;
>     };
> 
>-    var table = {
>-      ws: literal,
>-      "ws-pea": wsPea,
>-      "ws-tpea": wsTPea,
>-      "line-comment": lineComment,
>-      "multiline-comment": multilineComment,
>-      "interface": interface_,
>-      operation: operation,
>-      attribute: attribute,
>-      dictionary: dictionary,
>-      field: field,
>-      exception: exception,
>-      "const": const_,
>-      typedef: typedef,
>-      "implements": implements_,
>-      callback: callback,
>-      "enum": enum_,
>-      serializer: serializer,
>-      iterable: iterable,
>-      legacyiterable: legacyiterable,
>-      maplike: maplike,
>-      setlike: setlike,
>+    const table = {
>+      interface: interface_,
>+      "interface mixin": interface_mixin,
>+      namespace,
>+      operation,
>+      attribute,
>+      dictionary,
>+      field,
>+      const: const_,
>+      typedef,
>+      implements: implements_,
>+      includes,
>+      callback,
>+      enum: enum_,
>+      iterable,
>+      legacyiterable,
>+      maplike,
>+      setlike,
>       "callback interface": callbackInterface
>     };
>-    var dispatch = function(it) {
>+    function dispatch(it) {
>+      const dispatcher = table[it.type];
>+      if (!dispatcher) {
>+        throw new Error(`Type "${it.type}" is unsupported`)
>+      }
>       return table[it.type](it);
>     };
>-    var iterate = function(things) {
>+    function iterate(things) {
>       if (!things) return;
>-      var ret = "";
>-      for (var i = 0, n = things.length; i < n; i++) ret += dispatch(things[i]);
>+      let ret = "";
>+      for (const thing of things) ret += dispatch(thing);
>       return ret;
>     };
>     return iterate(ast);
>   };
> 
> 
>-  var obj = {
>-    write: function(ast, opt) {
>-      if (!opt) opt = {};
>-      return write(ast, opt);
>-    }
>+  const obj = {
>+    write
>   };
> 
>   if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
>     module.exports = obj;
>   } else if (typeof define === 'function' && define.amd) {
>-    define([], function() {
>-      return obj;
>-    });
>+    define([], () => obj);
>   } else {
>     (self || window).WebIDL2Writer = obj;
>   }
>-}());
>+})();
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package-lock.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package-lock.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..b0581037fe943423f4f09bceabbef0f8828d6fc3
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package-lock.json
>@@ -0,0 +1,700 @@
>+{
>+  "name": "webidl2",
>+  "version": "13.0.3",
>+  "lockfileVersion": 1,
>+  "requires": true,
>+  "dependencies": {
>+    "@babel/code-frame": {
>+      "version": "7.0.0-beta.40",
>+      "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.0.0-beta.40.tgz",
>+      "integrity": "sha512-eVXQSbu/RimU6OKcK2/gDJVTFcxXJI4sHbIqw2mhwMZeQ2as/8AhS9DGkEDoHMBBNJZ5B0US63lF56x+KDcxiA==",
>+      "dev": true,
>+      "requires": {
>+        "@babel/highlight": "7.0.0-beta.40"
>+      }
>+    },
>+    "@babel/highlight": {
>+      "version": "7.0.0-beta.40",
>+      "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.0.0-beta.40.tgz",
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>+          }
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>+      "integrity": "sha1-GrKLVW4Zg2Oowab35vogE3/mrtk=",
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>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package.json
>index 02b2a9d9b1644eb6e614fa7394ad6c0dde1fed86..92faccafa813fb607f5be73a07cda7f7079d63d5 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package.json
>@@ -1,21 +1,27 @@
> {
>   "name": "webidl2",
>   "description": "A WebIDL Parser",
>-  "version": "2.4.0",
>-  "author": "Robin Berjon <robin@berjon.com>",
>-  "license": "MIT",
>+  "version": "13.0.3",
>+  "contributors": [
>+    "Robin Berjon <robin@berjon.com> (https://berjon.com)",
>+    "Marcos Caceres <marcos@marcosc.com> (https://marcosc.com)",
>+    "Kagami Sascha Rosylight <saschaplas@outlook.com>",
>+    "Timothy Gu <timothygu99@gmail.com>"
>+  ],
>+  "license": "W3C",
>   "dependencies": {},
>   "devDependencies": {
>-    "mocha": "3.2.0",
>-    "expect": "1.20.2",
>-    "underscore": "1.8.3",
>-    "jsondiffpatch": "0.2.4",
>-    "benchmark": "*",
>-    "microtime": "2.1.3"
>+    "expect": "22.4.0",
>+    "jsondiffpatch": "0.3.5",
>+    "mocha": "5.0.4"
>   },
>   "scripts": {
>-    "test": "mocha"
>+    "test": "mocha",
>+    "acquire": "node test/util/acquire.js"
>   },
>-  "repository": "git://github.com/darobin/webidl2.js",
>-  "main": "index"
>+  "repository": "git://github.com/w3c/webidl2.js",
>+  "main": "index.js",
>+  "files": [
>+    "lib/*"
>+  ]
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid.js
>index b8ab3a1866de0f05d23b2999f97a216e8b789c7e..19bbf006e579ef5997ae23c01decf28c0b0acb68 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid.js
>@@ -1,42 +1,20 @@
>-
> // NOTES:
> //  - the errors actually still need to be reviewed to check that they
> //    are fully correct interpretations of the IDLs
> 
>-var wp = process.env.JSCOV ? require("../lib-cov/webidl2") : require("../lib/webidl2")
>-,   expect = require("expect")
>-,   pth = require("path")
>-,   fs = require("fs")
>-;
>-describe("Parses all of the invalid IDLs to check that they blow up correctly", function () {
>-    var dir = pth.join(__dirname, "invalid/idl")
>-    ,   skip = {}
>-    ,   idls = fs.readdirSync(dir)
>-                  .filter(function (it) { return (/\.w?idl$/).test(it) && !skip[it]; })
>-                  .map(function (it) { return pth.join(dir, it); })
>-    ,   errors = idls.map(function (it) { return pth.join(__dirname, "invalid", "json", pth.basename(it).replace(/\.w?idl/, ".json")); })
>-    ;
>+"use strict";
> 
>-    for (var i = 0, n = idls.length; i < n; i++) {
>-        var idl = idls[i], error = JSON.parse(fs.readFileSync(errors[i], "utf8"));
>-        var func = (function (idl, err) {
>-            return function () {
>-                var error;
>-                try {
>-                    var ast = wp.parse(fs.readFileSync(idl, "utf8"));
>-                    console.log(JSON.stringify(ast, null, 4));
>-                }
>-                catch (e) {
>-                    error = e;
>-                }
>-                finally {
>-                    expect(error).toExist();
>-                    expect(error.message).toEqual(err.message);
>-                    expect(error.line).toEqual(err.line);
>-                }
>+const { collect } = require("./util/collect");
>+const fs = require("fs");
>+const expect = require("expect");
> 
>-            };
>-        }(idl, error));
>-        it("should produce the right error for " + idl, func);
>-    }
>+describe("Parses all of the invalid IDLs to check that they blow up correctly", () => {
>+  for (const test of collect("invalid", { expectError: true })) {
>+    it(`should produce the right error for ${test.path}`, () => {
>+      const err = test.readJSON();
>+      expect(test.error).toBeTruthy();
>+      expect(test.error.message).toEqual(err.message);
>+      expect(test.error.line).toEqual(err.line);
>+    });
>+  }
> });
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/array.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/array.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..58a8618ab648579247a8cd00ac9dc4a585faf6b8
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/array.widl
>@@ -0,0 +1,6 @@
>+// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>+// T[] is removed by https://github.com/heycam/webidl/commit/079cbb861a99e9e857a3f2a169c0beeb49cd020a
>+[Constructor]
>+interface LotteryResults {
>+  readonly attribute unsigned short[][] numbers;
>+};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/caller.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/caller.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..26fedc33f9402c651ebd15629a8fcb7212102120
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/caller.widl
>@@ -0,0 +1,7 @@
>+// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>+// legacycallers are removed by https://github.com/heycam/webidl/pull/412
>+
>+interface NumberQuadrupler {
>+  // This operation simply returns four times the given number x.
>+  legacycaller float compute(float x);
>+};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/duplicate.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/duplicate.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..4916af34273d30dd7579a9be362c5f8deb65df36
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/duplicate.widl
>@@ -0,0 +1,5 @@
>+typedef int Test;
>+
>+interface Test {
>+  void foo();
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-empty.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-empty.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..7f189eb62c1bd2b6d710532b8042a459d7ba1b1f
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-empty.widl
>@@ -0,0 +1 @@
>+enum Empty {};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-wo-comma.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-wo-comma.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..ebc53065ededed62d27c87ae3b1b661874d3c715
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-wo-comma.widl
>@@ -0,0 +1 @@
>+enum NoComma { "value1" "value2" };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/exception.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/exception.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..a0ea2e47e20833641440b095a9b2d2d02f4504b7
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/exception.widl
>@@ -0,0 +1,6 @@
>+// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>+// IDL exceptions are removed by https://github.com/heycam/webidl/commit/50e172ec079db073c3724c9beac1b576fb5dbc47
>+
>+exception SomeException {
>+};
>+
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/extattr-empty-ids.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/extattr-empty-ids.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..93c48c3ade5fa448cddd3399f0d41de56268f2af
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/extattr-empty-ids.widl
>@@ -0,0 +1,2 @@
>+[Exposed=()]
>+interface Unexposed {};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/id-underscored-number.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/id-underscored-number.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..d00121fd54f2f31903fb7592f5d6e438b697a4fb
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/id-underscored-number.widl
>@@ -0,0 +1 @@
>+interface _0 {};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/implements_and_includes_ws.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/implements_and_includes_ws.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..6666daed00c3e7d9b7f64970030a2d46a38e4967
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/implements_and_includes_ws.widl
>@@ -0,0 +1,4 @@
>+// This hits the unshifting of whitespace in the "implements" and
>+// "includes" productions. If there is a bug in that whitespace
>+// rollback, the wrong exception will be produced.
>+foobar;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/iterator.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/iterator.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..3bf1b36dec675656cbfd7ea4603617b3db91bfc6
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/iterator.widl
>@@ -0,0 +1,35 @@
>+interface SessionManager {
>+  Session getSessionForUser(DOMString username);
>+  readonly attribute unsigned long sessionCount;
>+
>+  Session iterator;
>+};
>+
>+interface Session {
>+  readonly attribute DOMString username;
>+  // ...
>+};
>+
>+interface SessionManager2 {
>+  Session2 getSessionForUser(DOMString username);
>+  readonly attribute unsigned long sessionCount;
>+
>+  Session2 iterator = SessionIterator;
>+};
>+
>+interface Session2 {
>+  readonly attribute DOMString username;
>+  // ...
>+};
>+
>+interface SessionIterator {
>+  readonly attribute unsigned long remainingSessions;
>+};
>+
>+     interface NodeList {
>+       Node iterator = NodeIterator;
>+     };
>+
>+     interface NodeIterator {
>+       Node iterator object;
>+     };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl
>index 33c274b8b9a88605ed538b270ff6f5c7d0762016..efb5c14ffd626f7719277ee3892fce5fb664ec45 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl
>@@ -1,3 +1,3 @@
> interface MapLikeOneType {
>-	maplike<long>;
>+  maplike<long>;
> }
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/namespace-readwrite.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/namespace-readwrite.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..e184133228458e91cff2cc88fcf3ee87fff92e3f
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/namespace-readwrite.widl
>@@ -0,0 +1,3 @@
>+namespace CSS {
>+  attribute object readwrite;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon-callback.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon-callback.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..cb2055718e5f044a671424532eee6afe577bebc2
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon-callback.widl
>@@ -0,0 +1,7 @@
>+callback interface NoSemicolon {
>+  attribute boolean noSemiColon;
>+}
>+
>+enum YouNeedOne {
>+  "really"
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..10bc716249b3e1fa40faacb7298ee3b1f7b673bf
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon.widl
>@@ -0,0 +1,7 @@
>+partial interface NoSemicolon {
>+  attribute boolean noSemiColon;
>+}
>+
>+enum YouNeedOne {
>+  "really"
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl
>index 1deac5aeec90815102bf41fc437da2c962eaefac..6c875ff04b52312bc55f737347e9924c26847cd8 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl
>@@ -1,5 +1,6 @@
> interface Foo {};
> 
> interface NonNullable {
>-  attribute Foo?? foo;
>-};
>\ No newline at end of file
>+  attribute Foo??
>+    foo;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-nullable.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-nullable.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..894d7c044b2a5b4e9d30427cd913df7b709bdfa5
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-nullable.widl
>@@ -0,0 +1,4 @@
>+interface X {
>+    attribute Promise<void>?
>+        promise;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-with-extended-attribute.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-with-extended-attribute.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..0ce171fec33e72d36168ad0d731c5199adb8b08e
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-with-extended-attribute.widl
>@@ -0,0 +1,3 @@
>+interface Foo {
>+  Promise<[XAttr] DOMString> foo(any param);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl
>index fc4ae2be908446e336cadd84c475cb7462b0b355..6057aa1feba64ebce61c9ec067f6250f036efa0e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl
>@@ -1,3 +1,3 @@
> interface ReadonlyIterable {
>-	readonly iterable<long>;
>+  readonly iterable<long>;
> }
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-key-with-extended-attribute.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-key-with-extended-attribute.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..c11eb7414b0b8fcd9f2f6a1833bc764185b051fe
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-key-with-extended-attribute.widl
>@@ -0,0 +1,3 @@
>+interface Foo {
>+  void foo(record<[XAttr] DOMString, any> param);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-single.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-single.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..84db40282433b85f6a29cd236fdd51afe42c53a8
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-single.widl
>@@ -0,0 +1,3 @@
>+interface Foo {
>+  void foo(record<DOMString> param);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl
>index 1ecae22c0106cc9b8e5b30d6af3dfeeefb3dc22b..c2681bc75f1e8b38a2b83ce9ee5a262fbdcda762 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl
>@@ -1,3 +1,3 @@
> interface SetLikeTwoTypes {
>-	setlike<long, long>;
>+  setlike<long, long>;
> }
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setter-creator.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setter-creator.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..a70b26774d722f99119b8e7ce975b11627338145
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setter-creator.widl
>@@ -0,0 +1,4 @@
>+// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>+interface OrderedMap {
>+  setter creator void set(DOMString name, any value);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-negative-infinity.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-negative-infinity.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..3d71222e54b5929062fc7b2080b99107e9f119c2
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-negative-infinity.widl
>@@ -0,0 +1,3 @@
>+interface X {
>+    const float infinity = - Infinity;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-variadic.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-variadic.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..6d77e186d6670fd0351934db12be01f7d4aff01a
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-variadic.widl
>@@ -0,0 +1,3 @@
>+interface X {
>+    void operation(object . . . args);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl
>index bdfbfa709733f9faa6672ac3953b4673f283092f..dd0c1b18589979c4baba301a6e792bb1d1eca4e1 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl
>@@ -1,5 +1,5 @@
> // Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>-// omittable is no longer a recognized keywoard as of 20110905
>+// omittable is no longer a recognized keyword as of 20110905
> interface Dictionary {
>   readonly attribute unsigned long propertyCount;
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stray-slash.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stray-slash.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..b673aa94b01d65a0b666879f8c899c86111c7ab4
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stray-slash.widl
>@@ -0,0 +1,2 @@
>+// This is a comment.
>+/ This is not.
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.idl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.idl
>deleted file mode 100644
>index 44fd3ff136ee5671637d02cb80964ddba092a658..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.idl
>+++ /dev/null
>@@ -1,3 +0,0 @@
>-interface Util {
>-  const DOMString hello = "world";
>-};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..44fd3ff136ee5671637d02cb80964ddba092a658
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.widl
>@@ -0,0 +1,3 @@
>+interface Util {
>+  const DOMString hello = "world";
>+};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl
>index 106f30b8f72ec7df496302b4a03ddddb55bf7f19..dfd377bf932b98cceeeb69755e8eacfa38417ae0 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl
>@@ -19,4 +19,4 @@
>     boolean allPointsWithinBounds(PointSequence ps);
>   };
> 
>-  typedef [Clamp] octet value; 
>\ No newline at end of file
>+  typedef [Clamp] octet value;
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-dangling-or.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-dangling-or.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..0aa043e9aca9587dfb5c44ef96477b98d5215ed4
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-dangling-or.widl
>@@ -0,0 +1 @@
>+typedef (One or Two or) UnionOr;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-one.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-one.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..86ee96f516d63536a17bf1ef5cb8d178dc0ca326
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-one.widl
>@@ -0,0 +1 @@
>+typedef (OnlyOne) UnionOne;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-zero.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-zero.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..177fc4c708f901c089983317b5dbce23941329b1
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-zero.widl
>@@ -0,0 +1 @@
>+typedef () UnionZero;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/unknown-generic.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/unknown-generic.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..ee4a2db74a63bdef11d2920e6b698b7b4dc0f155
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/unknown-generic.widl
>@@ -0,0 +1,3 @@
>+interface FetchEvent : Event {
>+  ResponsePromise<any> default();
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/w3c-import.log
>index 6a3f4930a4eb7f3dbf3a4e17fd2aea3dc26d3550..f2ceb4df6ec7d56de91e80d85d8e3a429db03d5c 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -14,18 +14,43 @@ Property values requiring vendor prefixes:
> None
> ------------------------------------------------------------------------
> List of files:
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/array.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/caller.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/dict-required-default.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/duplicate.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-empty.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum-wo-comma.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/enum.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/exception.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/extattr-empty-ids.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/id-underscored-number.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/implements_and_includes_ws.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/iterator.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/maplike-1type.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/module.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/namespace-readwrite.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon-callback.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/no-semicolon.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableany.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/nonnullableobjects.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-nullable.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/promise-with-extended-attribute.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/raises.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/readonly-iterable.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-key-with-extended-attribute.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-key.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/record-single.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/scopedname.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/sequenceAsAttribute.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setlike-2types.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/setter-creator.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-negative-infinity.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/spaced-variadic.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/special-omittable.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.idl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stray-slash.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/stringconstants.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/typedef-nested.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-dangling-or.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-one.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/union-zero.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/idl/unknown-generic.widl
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/array.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/array.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..898b2d836bff81330d734e0ba10372e9772fd523
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/array.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface LotteryResults`: No name in attribute",
>+    "line": 5
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/caller.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/caller.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..567fa3368129f9b6d54bb3bb4c0f9d4d50186525
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/caller.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface NumberQuadrupler`: Invalid operation",
>+    "line": 6
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json
>index c5afeca85c05debc159481b3e8344aa87fd96da2..82b6b2ae42a6f61a20a32bcb67f44461ba7adae1 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Required member must not have a default"
>+    "message":  "Got an error during or right after parsing `dictionary Dict`: Required member must not have a default"
> ,   "line":     4
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/duplicate.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/duplicate.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..e88a7156fe8c1c602ebe1ae8d66cbeebe69ff060
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/duplicate.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `typedef Test`: The name \"Test\" of type \"typedef\" is already seen",
>+    "line": 3
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-empty.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-empty.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..734bc67de1fd67e98c8c8d78bde45c62fb3201ed
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-empty.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `enum Empty`: No value in enum",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-wo-comma.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-wo-comma.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..bfd0b0951fce8d25739d2e18a027e7fc600d9b14
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-wo-comma.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `enum NoComma`: No comma between enum values",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum.json
>index 166115801c3411b8faf7d3e9bccbe4a022a02b0e..073ff6c290cafdf614909b8f6ef27ba0a4c5829d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Unexpected value in enum"
>+    "message":  "Got an error during or right after parsing `enum foo`: Unexpected value in enum"
> ,   "line":     1
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/exception.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/exception.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..ad9fac6ca2f64e7083421516a9ceb9e6397555ec
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/exception.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: Unrecognised tokens",
>+    "line": 4
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/extattr-empty-ids.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/extattr-empty-ids.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..4337f1e180c28881514845d54557819674a76418
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/extattr-empty-ids.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: Expected identifiers but not found",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/id-underscored-number.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/id-underscored-number.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..419ed946fca05c2097ff3c2c48b91cb11e5a1b2a
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/id-underscored-number.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: No name for interface",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/implements_and_includes_ws.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/implements_and_includes_ws.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..ad9fac6ca2f64e7083421516a9ceb9e6397555ec
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/implements_and_includes_ws.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: Unrecognised tokens",
>+    "line": 4
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/iterator.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/iterator.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..e46d653ae3c51293d584045cdadd6c0a301206fe
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/iterator.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface SessionManager`: Invalid operation",
>+    "line": 5
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json
>index 859a820a4910cd1592dd52b31adebb013409f917..75e7a35ee256e91357994ff8a85b1828cb48112e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json
>@@ -1,4 +1,4 @@
> {
>-    "message": "Missing second type argument in maplike declaration",
>+    "message": "Got an error during or right after parsing `interface MapLikeOneType`: Missing second type argument in maplike declaration",
>     "line": 2
>-}
>\ No newline at end of file
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/module.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/module.json
>index 3b0984d973f45e32c56dd76d6d8b7fd6d8beb220..9c071cdd07a7a39ed18592e82100d8d50065a030 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/module.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/module.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Unrecognised tokens"
>+    "message":  "Got an error before parsing any named definition: Unrecognised tokens"
> ,   "line":     2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/namespace-readwrite.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/namespace-readwrite.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..d21215111f1ee27ae73df035349c576c64362a43
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/namespace-readwrite.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `namespace CSS`: Attributes must be readonly in this context",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon-callback.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon-callback.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..1db9d14c8e2c51204a1e2a2d7d1e98c3066106ef
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon-callback.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `callback interface NoSemicolon`: Missing semicolon after interface",
>+    "line": 5
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..087532a012f59276976b70b1709e927c2ddd0797
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `partial interface NoSemicolon`: Missing semicolon after interface",
>+    "line": 5
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json
>index cf5229e8e44ab096ae16c22e0b0b04c392fcb28b..8a1f90046ae4d9df8c58bf17e0c2ed6bdc7c4fd0 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Type any cannot be made nullable"
>+    "message":  "Got an error during or right after parsing `interface NonNullable`: Type any cannot be made nullable"
> ,   "line":     2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json
>index 23cbb3e5d180f15a898743edbd7ec400a74b32f4..d470ec94a606c6caa01901d9724128d31111d216 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Can't nullable more than once"
>-,   "line":     4
>+    "message": "Got an error during or right after parsing `interface NonNullable`: Can't nullable more than once",
>+    "line": 4
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-nullable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-nullable.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..ced51faf1be4df756b4bc987356ad88ada0f0038
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-nullable.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface X`: Promise type cannot be nullable",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-with-extended-attribute.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-with-extended-attribute.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..71212d46e3c011aed64cb6b6008a4a1b427d14bf
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-with-extended-attribute.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface Foo`: Promise type cannot have extended attribute",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/raises.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/raises.json
>index 8b67afe4fc9702d3577aef8cf9f430662cd60119..3165b874f0c1891186b479b6460c0ae90a8533db 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/raises.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/raises.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Unterminated attribute"
>+    "message":  "Got an error during or right after parsing `interface Person`: Unterminated attribute"
> ,   "line":     5
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json
>index c6f52a24615883eddf581aa15d215b426859c4cb..a571b22271b80e1f863fdba263603518a71899b3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json
>@@ -1,4 +1,4 @@
> {
>-    "message": "Invalid operation",
>+    "message": "Got an error during or right after parsing `interface ReadonlyIterable`: Missing return type",
>     "line": 2
>-}
>\ No newline at end of file
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key-with-extended-attribute.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key-with-extended-attribute.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..4002e7fe0155d5bc2d615d55a4e4e976e13e38a8
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key-with-extended-attribute.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface Foo`: Record key cannot have extended attribute",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key.json
>index 3b929b926a30a7d0b776961ee5135fae3ae57265..6f1bb99be9080873adc0c7c685dca0d55c2b67ec 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key.json
>@@ -1,4 +1,4 @@
> {
>-    "message": "Record key must be DOMString, USVString, or ByteString",
>+    "message": "Got an error during or right after parsing `interface Foo`: Record key must be a string type",
>     "line": 2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-single.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-single.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..ece4fb2fee3c07c3aa6241e3c0cb6ed5477257db
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-single.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface Foo`: Missing comma after record key type",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json
>index 8e2cd803287ef4fce3812c5ea55cfdc87c01e31f..4620d2df5fa0cc254a6d6cd3c6b75147c658b40a 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "No name in typedef"
>+    "message":  "Got an error before parsing any named definition: No name in typedef"
> ,   "line":     2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json
>index b714f5d92434a2cc45630336b33d7645556c329c..5b4314a6de128dc602ae1dec4601a00f86c111bf 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Attributes cannot accept sequence types"
>+    "message":  "Got an error during or right after parsing `interface sequenceAsAttribute`: Attributes cannot accept sequence types"
> ,   "line":     2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json
>index c9e49b6756d5d900a0c1b18a440e62b4811a1d3b..2900e1bac300742cec71ee8f66977bde9b9c60ac 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json
>@@ -1,4 +1,4 @@
> {
>-    "message": "Unterminated setlike declaration",
>+    "message": "Got an error during or right after parsing `interface SetLikeTwoTypes`: Unterminated setlike declaration",
>     "line": 2
>-}
>\ No newline at end of file
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setter-creator.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setter-creator.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..25decb374e12fe27f05979e40d7f30647395be16
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setter-creator.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface OrderedMap`: Invalid operation",
>+    "line": 3
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-negative-infinity.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-negative-infinity.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..9e5d61804990bb8a99e1c863b2c73bb8eb5ee142
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-negative-infinity.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface X`: No value for const",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-variadic.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-variadic.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..0090abeeb71b23148a5d9ccd2a3bff927774ed5d
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-variadic.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface X`: Unterminated operation",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json
>index 7acb08834b0e6eaf0ece877b63466eadb42a5299..c20b28e03c17d6df29e2ca1b7ee948f579ff3f27 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Invalid operation"
>+    "message":  "Got an error during or right after parsing `interface Dictionary`: Invalid operation"
> ,   "line":     6
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stray-slash.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stray-slash.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..9c071cdd07a7a39ed18592e82100d8d50065a030
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stray-slash.json
>@@ -0,0 +1,4 @@
>+{
>+    "message":  "Got an error before parsing any named definition: Unrecognised tokens"
>+,   "line":     2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json
>index d5bf1a8832c664a02c488f70df005311d30b926a..745d6e6e08ba2238002d27bb5bc4a7e0c6c01bfa 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "No value for const"
>+    "message":  "Got an error during or right after parsing `interface Util`: No type for const"
> ,   "line":     2
> }
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json
>index d7fb9182f86e9d3db758763f472e2ab056fcaf09..e1843cec7d93e4f7df588724a4fe3985ec53c48b 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json
>@@ -1,4 +1,4 @@
> {
>-    "message":  "Invalid operation"
>+    "message":  "Got an error during or right after parsing `interface Widget`: Missing return type"
> ,   "line":     14
>-}
>\ No newline at end of file
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-dangling-or.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-dangling-or.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..68dfd8b2ae60986b15ab06b4bd90c3a9a1f64d5b
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-dangling-or.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: No type after open parenthesis or 'or' in union type",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-one.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-one.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..476403d6889be7754ff7d2fa65edbe31b4bb4ea1
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-one.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: At least two types are expected in a union type but found less",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-zero.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-zero.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..68dfd8b2ae60986b15ab06b4bd90c3a9a1f64d5b
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-zero.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error before parsing any named definition: No type after open parenthesis or 'or' in union type",
>+    "line": 1
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/unknown-generic.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/unknown-generic.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..3703db3b2ab332bb1754e01f0e8dbe012a3f99d7
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/unknown-generic.json
>@@ -0,0 +1,4 @@
>+{
>+    "message": "Got an error during or right after parsing `interface FetchEvent`: Unsupported generic type ResponsePromise",
>+    "line": 2
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/w3c-import.log
>index 7bc368eafaa544d2ea457f2748b2eeb4a509cec8..30181bf61575c8c9259cdd17111f5f7c597d992a 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -14,18 +14,43 @@ Property values requiring vendor prefixes:
> None
> ------------------------------------------------------------------------
> List of files:
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/array.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/caller.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/dict-required-default.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/duplicate.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-empty.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum-wo-comma.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/enum.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/exception.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/extattr-empty-ids.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/id-underscored-number.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/implements_and_includes_ws.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/iterator.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/maplike-1type.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/module.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/namespace-readwrite.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon-callback.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/no-semicolon.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableany.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/nonnullableobjects.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-nullable.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/promise-with-extended-attribute.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/raises.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/readonly-iterable.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key-with-extended-attribute.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-key.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/record-single.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/scopedname.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/sequenceAsAttribute.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setlike-2types.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/setter-creator.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-negative-infinity.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/spaced-variadic.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/special-omittable.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stray-slash.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/stringconstants.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/typedef-nested.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-dangling-or.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-one.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/union-zero.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid/json/unknown-generic.json
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax.js
>index 3b343e4229d5027d9fe081418d2d5fb47d49a8f5..05d647eda103945b0633bef0b53ee789268165d3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax.js
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax.js
>@@ -1,41 +1,19 @@
>+"use strict";
> 
>-var wp = process.env.JSCOV ? require("../lib-cov/webidl2") : require("../lib/webidl2")
>-,   expect = require("expect")
>-,   pth = require("path")
>-,   fs = require("fs")
>-,   jdp = require("jsondiffpatch")
>-,   debug = true
>-;
>-describe("Parses all of the IDLs to produce the correct ASTs", function () {
>-    var dir = pth.join(__dirname, "syntax/idl")
>-    ,   skip = {} // use if we have a broken test
>-    ,   idls = fs.readdirSync(dir)
>-                  .filter(function (it) { return (/\.widl$/).test(it) && !skip[it]; })
>-                  .map(function (it) { return pth.join(dir, it); })
>-    ,   jsons = idls.map(function (it) { return pth.join(__dirname, "syntax/json", pth.basename(it).replace(".widl", ".json")); })
>-    ;
>+const { collect } = require("./util/collect");
>+const expect = require("expect");
>+const debug = true;
> 
>-    for (var i = 0, n = idls.length; i < n; i++) {
>-        var idl = idls[i], json = jsons[i];
>-
>-        var func = (function (idl, json) {
>-            return function () {
>-                try {
>-                    var optFile = pth.join(__dirname, "syntax/opt", pth.basename(json));
>-                    var opt = undefined;
>-                    if (fs.existsSync(optFile))
>-                        opt = JSON.parse(fs.readFileSync(optFile, "utf8"));
>-                    var diff = jdp.diff(JSON.parse(fs.readFileSync(json, "utf8")),
>-                                        wp.parse(fs.readFileSync(idl, "utf8"), opt));
>-                    if (diff && debug) console.log(JSON.stringify(diff, null, 4));
>-                    expect(diff).toBe(undefined);
>-                }
>-                catch (e) {
>-                    console.log(e.toString());
>-                    throw e;
>-                }
>-            };
>-        }(idl, json));
>-        it("should produce the same AST for " + idl, func);
>-    }
>+describe("Parses all of the IDLs to produce the correct ASTs", () => {
>+  for (const test of collect("syntax")) {
>+    it(`should produce the same AST for ${test.path}`, () => {
>+      try {
>+        expect(test.diff()).toBeFalsy();
>+      }
>+      catch (e) {
>+        console.log(e.toString());
>+        throw e;
>+      }
>+    });
>+  }
> });
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/array.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/array.widl
>deleted file mode 100644
>index 22e21fb6564738bd56830ce0300da389ce0574bf..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/array.widl
>+++ /dev/null
>@@ -1,5 +0,0 @@
>-// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>-[Constructor]
>-interface LotteryResults {
>-  readonly attribute unsigned short[][] numbers;
>-};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl
>index 7e1d691cbe28afdc58082a7fd81cbdb4f37cf456..f665c1fc47276f700dabab71f869c0b0ead28163 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl
>@@ -1,9 +1,4 @@
> // Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>-exception InvalidName {
>-  DOMString reason;
>-};
>-
>-exception NoSuchPet { };
> 
> interface Person {
> 
>@@ -11,4 +6,6 @@ interface Person {
>   // short can take.
>   attribute unsigned short age;
> 
>-};
>\ No newline at end of file
>+  // required is an allowed attribute name
>+  attribute any required;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/caller.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/caller.widl
>deleted file mode 100644
>index 92acb1c017631f04762f8d68e0462e10d3739dad..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/caller.widl
>+++ /dev/null
>@@ -1,5 +0,0 @@
>-// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>-interface NumberQuadrupler {
>-  // This operation simply returns four times the given number x.
>-  legacycaller float compute(float x);
>-};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl
>index 5e28ae9c116a9d9262ea9e59e5b95350a1ce613f..043b022b6462eed600c8a9ceab87d1ebaef5ea18 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl
>@@ -8,11 +8,4 @@ interface Util {
>   const unrestricted float sobig = Infinity;
>   const unrestricted double minusonedividedbyzero = -Infinity;
>   const short notanumber = NaN;
>-};
>-
>-exception Error {
>-  const short ERR_UNKNOWN = 0;
>-  const short ERR_OUT_OF_MEMORY = 1;
>-
>-  short errorCode;
> };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl
>index 6b3e0eda284ad71f7b3ad6221a15214d4fc0fc23..6ffeb3c20a1a47209ceb2ec2441f62be3f553158 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl
>@@ -7,7 +7,7 @@ interface Dictionary {
> };
> 
> 
>-interface Dictionary {
>+interface Dictionary2 {
>   readonly attribute unsigned long propertyCount;
> 
>   float getProperty(DOMString propertyName);
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception-inheritance.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception-inheritance.widl
>deleted file mode 100644
>index 258fdeba6f43d36a2a8d7927b695d53a5cc5d2e3..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception-inheritance.widl
>+++ /dev/null
>@@ -1,7 +0,0 @@
>-// from http://lists.w3.org/Archives/Public/public-script-coord/2010OctDec/0112.html
>-  exception DOMException {
>-    unsigned short code;
>-  };
>-
>-  exception HierarchyRequestError : DOMException { };
>-  exception NoModificationAllowedError : DOMException { };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception.widl
>deleted file mode 100644
>index f4b6ae29e10ddb18ffa5fc2b6201f923cb1ad50d..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception.widl
>+++ /dev/null
>@@ -1,8 +0,0 @@
>-// Extracted from http://dev.w3.org/2006/webapi/WebIDL/ on 2011-05-06
>-interface Dahut {
>-  attribute DOMString type;
>-};
>-
>-exception SomeException {
>-};
>-
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl
>index c1df79e142d54dbf9bd4c3c298b0c270e679ffc2..57d4f97de7c3176b65e3da2aa7ed53d3db789fd9 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl
>@@ -2,10 +2,28 @@
> 
> [Global=(Worker,ServiceWorker), Exposed=ServiceWorker]
> interface ServiceWorkerGlobalScope : WorkerGlobalScope {
>-  
>+
> };
> 
> // Conformance with ExtendedAttributeList grammar in http://www.w3.org/TR/WebIDL/#idl-extended-attributes
> // Section 3.11
> [IntAttr=0, FloatAttr=3.14, StringAttr="abc"]
> interface IdInterface {};
>+
>+// Extracted from http://www.w3.org/TR/2016/REC-WebIDL-1-20161215/#Constructor on 2017-5-18 with whitespace differences
>+[
>+  Constructor,
>+  Constructor(double radius)
>+]
>+interface Circle {
>+  attribute double r;
>+  attribute double cx;
>+  attribute double cy;
>+  readonly attribute double circumference;
>+};
>+
>+// Extracted from https://heycam.github.io/webidl/#idl-annotated-types on 2017-12-15
>+[Exposed=Window]
>+interface I {
>+    attribute [XAttr] (long or Node) attrib;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl
>index 02b64572a426abc69e4247563eb1d4797aec321e..693cd324e96b85dbb4ff25d2c9d8dd1edbf495b3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl
>@@ -1,17 +1,17 @@
> interface Foo {
>-  Promise<ResponsePromise<sequence<DOMString?>>> bar();
>-  readonly attribute Promise<DOMString>[] baz;
>+  Promise<Promise<sequence<DOMString?>>> bar();
>+  readonly attribute Promise<DOMString> baz;
> };
> 
> // Extracted from https://slightlyoff.github.io/ServiceWorker/spec/service_worker/ on 2014-05-08
> 
> interface ServiceWorkerClients {
>-  Promise<Client[]?> getServiced();
>+  Promise<Client?> getServiced();
>   Promise<any> reloadAll();
> };
> 
> // Extracted from https://slightlyoff.github.io/ServiceWorker/spec/service_worker/ on 2014-05-13
> 
> interface FetchEvent : Event {
>-  ResponsePromise<any> default();
>+  Promise<any> default();
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/identifier-qualified-names.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/identifier-qualified-names.widl
>index 33893d4c64498240b5cb84f19081dbd6f90e0d2a..c39f84b45a36cccd360a861b118c3723aeb3ef2d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/identifier-qualified-names.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/identifier-qualified-names.widl
>@@ -3,18 +3,6 @@
>   // Qualified name:    "::framework::number"
>   typedef float number;
> 
>-  // Exception identifier: "FrameworkException"
>-  // Qualified name:       "::framework::FrameworkException"
>-  exception FrameworkException {
>-
>-    // Constant identifier: "ERR_NOT_FOUND"
>-    // Qualified name:      "::framework::FrameworkException::ERR_NOT_FOUND"
>-    const long ERR_NOT_FOUND = 1;
>-
>-    // Exception field identifier: "code"
>-    long code;
>-  };
>-
>   // Interface identifier: "System"
>   // Qualified name:       "::framework::System"
>   interface System {
>@@ -27,7 +15,7 @@
>     getter DOMString (DOMString keyName);
>   };
> 
>-    
>+
>     // Interface identifier: "TextField"
>     // Qualified name:       "::framework::gui::TextField"
>     interface TextField {
>@@ -39,6 +27,7 @@
>       attribute DOMString? _value;
>     };
> 
>-interface Foo {
>- void op(object interface);
>-};
>\ No newline at end of file
>+interface FooEventTarget {
>+  // Argument names allow some selected keywords
>+  void addEventListener(EventListener? callback);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/indexed-properties.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/indexed-properties.widl
>index acf0ed3bf849f06b2fc1d375cb3a82488b3bd050..4b8aa9e353fac89c05ad21fe065b455e049268e3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/indexed-properties.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/indexed-properties.widl
>@@ -7,6 +7,6 @@ interface OrderedMap {
>   deleter void removeByIndex(unsigned long index);
> 
>   getter any get(DOMString name);
>-  setter creator void set(DOMString name, any value);
>+  setter void set(DOMString name, any value);
>   deleter void remove(DOMString name);
>-};
>\ No newline at end of file
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl
>index 558e8116494b2b3b5cf0ab5bc4f3c9f384aa906b..435b3ab3c8cd5877a1c096504f953dd287a8acfc 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl
>@@ -13,4 +13,10 @@ interface Person : Animal {
>   // Its getter behavior is inherited from Animal, and need not be specified
>   // the description of Person.
>   inherit attribute DOMString name;
>-};
>\ No newline at end of file
>+};
>+
>+interface Ghost : Person {
>+
>+  // An attribute that only inherits the getter behavior
>+  inherit readonly attribute DOMString name;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl
>index c7dfafa4daa808a225a1678ba52f350555de93c6..7f726f926fdecd72600c43e328f1e0bfb36f9be1 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl
>@@ -1,7 +1,11 @@
> interface IterableOne {
>-	iterable<long>;
>+  iterable<long>;
> };
> 
> interface IterableTwo {
>-	iterable<short, double?>;
>+  iterable<short, double?>;
>+};
>+
>+interface IterableThree {
>+  iterable<[XAttr] long>;
> };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterator.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterator.widl
>deleted file mode 100644
>index 3bf1b36dec675656cbfd7ea4603617b3db91bfc6..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterator.widl
>+++ /dev/null
>@@ -1,35 +0,0 @@
>-interface SessionManager {
>-  Session getSessionForUser(DOMString username);
>-  readonly attribute unsigned long sessionCount;
>-
>-  Session iterator;
>-};
>-
>-interface Session {
>-  readonly attribute DOMString username;
>-  // ...
>-};
>-
>-interface SessionManager2 {
>-  Session2 getSessionForUser(DOMString username);
>-  readonly attribute unsigned long sessionCount;
>-
>-  Session2 iterator = SessionIterator;
>-};
>-
>-interface Session2 {
>-  readonly attribute DOMString username;
>-  // ...
>-};
>-
>-interface SessionIterator {
>-  readonly attribute unsigned long remainingSessions;
>-};
>-
>-     interface NodeList {
>-       Node iterator = NodeIterator;
>-     };
>-
>-     interface NodeIterator {
>-       Node iterator object;
>-     };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl
>index eafa7cf0445947efee5d58bc1ff77376d166d8f0..9e1e9c527447a2bb2013baf28c31d3faddcac6ff 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl
>@@ -1,3 +1,3 @@
> interface LegacyIterable {
>-	legacyiterable<long>;
>+  legacyiterable<long>;
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl
>index 7b79b3888026a7693be7e46e10187290ebe2b1b4..437e381fef7673ecacc52362b5a30910c68156cd 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl
>@@ -1,7 +1,13 @@
> interface MapLike {
>-	maplike<long, float>;
>+  maplike<long, float>;
> };
> 
> interface ReadOnlyMapLike {
>-	readonly maplike<long, float>;
>+  readonly maplike<long, float>;
>+};
>+
>+// Extracted from https://heycam.github.io/webidl/#idl-type-extended-attribute-associated-with on 2017-07-01
>+
>+interface I {
>+    maplike<[XAttr2] DOMString, [XAttr3] long>;
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/mixin.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/mixin.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..7c37a6ee4207b31ddd2c48f9e1725721679e79e2
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/mixin.widl
>@@ -0,0 +1,12 @@
>+// Extracted from https://heycam.github.io/webidl/#using-mixins-and-partials on 2017-11-02
>+
>+interface mixin GlobalCrypto {
>+  readonly attribute Crypto crypto;
>+};
>+
>+Window includes GlobalCrypto;
>+WorkerGlobalScope includes GlobalCrypto;
>+
>+partial interface mixin WindowOrWorkerGlobalScope {
>+  readonly attribute Crypto crypto;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/overloading.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/overloading.widl
>index ef1288a887763dd78947de6b8786c00539474e97..52d8d15c1a13c81397bff5981d5745d9e42ea92d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/overloading.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/overloading.widl
>@@ -12,9 +12,9 @@ interface C {
>   void f(B x);
> };
> 
>-interface A {
>+interface D {
>   /* f1 */ void f(DOMString a);
>   /* f2 */ void f([AllowAny] DOMString a, DOMString b, float... c);
>   /* f3 */ void f();
>   /* f4 */ void f(long a, DOMString b, optional DOMString c, float... d);
>-};
>\ No newline at end of file
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl
>index 92939601a1a839cf7c48c3ed748eeb93bfa3febc..a91455ee192f192187e23728c78eaa6fda8d733f 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl
>@@ -9,11 +9,11 @@ interface Primitives {
>   attribute long long bigbig;
>   attribute  unsigned long long bigbigpositive;
>   attribute float real;
>-  attribute double bigreal; 
>+  attribute double bigreal;
>   attribute unrestricted float realwithinfinity;
>-  attribute unrestricted double bigrealwithinfinity; 
>-  attribute DOMString string; 
>-  attribute ByteString bytes; 
>+  attribute unrestricted double bigrealwithinfinity;
>+  attribute DOMString string;
>+  attribute ByteString bytes;
>   attribute Date date;
>   attribute RegExp regexp;
>-};
>\ No newline at end of file
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/promise-void.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/promise-void.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..c4eac3b75c46ac02a22c7682056cb32b5ecb4d89
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/promise-void.widl
>@@ -0,0 +1,3 @@
>+interface Cat {
>+    attribute Promise<void> meow;
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/record.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/record.widl
>index 6cdedb219bece6da8fdc98c739d341b599f71c99..dbfad3afbfeb6875725c977be301476292e48f41 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/record.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/record.widl
>@@ -2,7 +2,8 @@
> interface Foo {
>   void foo(sequence<record<ByteString, any>> param);
>   record<DOMString, (float or DOMString)?> bar();
>+};
> 
>-  // Make sure record can still be registered as a type.
>-  record baz();
>+interface Bar {
>+  record<DOMString, [XAttr] float> bar();
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl
>index 13997cb1d121ce106f49cfdcdeb9789074704842..338c8d427636fb340a00db9ec9b1ac51cfe15388 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl
>@@ -4,8 +4,6 @@ interface Dimensions {
>   attribute unsigned long height;
> };
> 
>-exception NoPointerDevice { };
>-
> interface Button {
> 
>   // An operation that takes no arguments, returns a boolean
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl
>index 6ba0d390d251a7df21c785d3c4b100ef23717cbe..b47c98225c71568e933139a902517bcf860a20e9 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl
>@@ -6,7 +6,8 @@ interface Canvas {
>   // ...
> };
> 
>-// Make sure sequence can still be registered as a type.
>-interface Foo {
>-  sequence bar();
>-};
>\ No newline at end of file
>+// Extracted from https://heycam.github.io/webidl/#idl-type-extended-attribute-associated-with on 2017-07-01
>+
>+interface I {
>+    void f1(sequence<[XAttr] long> arg);
>+};
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/serializer.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/serializer.widl
>deleted file mode 100644
>index 6f6ccd0e8d59e3e057f5ad0d2f65530b16a39359..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/serializer.widl
>+++ /dev/null
>@@ -1,64 +0,0 @@
>-interface Transaction {
>-  readonly attribute Account from;
>-  readonly attribute Account to;
>-  readonly attribute float amount;
>-  readonly attribute DOMString description;
>-  readonly attribute unsigned long number;
>-
>-  serializer;
>-};
>-
>-interface Account {
>-  attribute DOMString name;
>-  attribute unsigned long number;
>-  serializer DOMString serialize();
>-};
>-
>-interface Transaction2 {
>-  readonly attribute Account2 from;
>-  readonly attribute Account2 to;
>-  readonly attribute float amount;
>-  readonly attribute DOMString description;
>-  readonly attribute unsigned long number;
>-
>-  serializer = { from, to, amount, description };
>-};
>-
>-interface Account2 {
>-  attribute DOMString name;
>-  attribute unsigned long number;
>-  serializer = number;
>-};
>-
>-interface Account3 {
>-  attribute DOMString name;
>-  attribute unsigned long number;
>-
>-  serializer = { attribute };
>-};
>-
>-interface Account4 {
>-  getter object getItem(unsigned long index);
>-  serializer = { getter };
>-};
>-
>-interface Account5 : Account {
>-  attribute DOMString secondname;
>-  serializer = { inherit, secondname };
>-};
>-
>-interface Account6 : Account {
>-  attribute DOMString secondname;
>-  serializer = { inherit, attribute };
>-};
>-
>-interface Account7 {
>-  attribute DOMString name;
>-  attribute unsigned long number;
>-  serializer = [ name, number ];
>-};
>-
>-interface Account8 {
>-  getter object getItem(unsigned long index);
>-  serializer = [ getter ];
>-};
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl
>index 890e8e5a7597dde08c2fa7cb95461baddde69bba..4512f286b59a506fcbb957befe24a081b097d73e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl
>@@ -1,7 +1,11 @@
> interface SetLike {
>-	setlike<long>;
>+  setlike<long>;
> };
> 
> interface ReadOnlySetLike {
>-	readonly setlike<long>;
>+  readonly setlike<long>;
>+};
>+
>+interface SetLikeExt {
>+  setlike<[XAttr] long>;
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl
>index 4eb483d9b53861a104f712d942af3b10566023c5..c45277ea8db3377952b4bfa8a040aadb1d1c340e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl
>@@ -3,6 +3,6 @@ interface A {
>   stringifier DOMString ();
> };
> 
>-interface A {
>+interface B {
>   stringifier;
> };
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.idl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.idl
>deleted file mode 100644
>index 3048703e0c5541d5ca69f51870f219abf3745b44..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.idl
>+++ /dev/null
>@@ -1,4 +0,0 @@
>-  typedef (ImageData or
>-           HTMLImageElement or
>-           HTMLCanvasElement or
>-           HTMLVideoElement) TexImageSource;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.widl
>new file mode 100644
>index 0000000000000000000000000000000000000000..3048703e0c5541d5ca69f51870f219abf3745b44
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.widl
>@@ -0,0 +1,4 @@
>+  typedef (ImageData or
>+           HTMLImageElement or
>+           HTMLCanvasElement or
>+           HTMLVideoElement) TexImageSource;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl
>index 95e31c1690236ce77703c9a3ca03e88e5ba1fc06..beaaa8726009e6b1a3ffe3aafd5f89bf7cafe4bb 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl
>@@ -1,3 +1,3 @@
> interface Suffixes {
>-  void test(sequence<DOMString[]?>? foo);
>+  void test(sequence<DOMString?>? foo);
> };
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/w3c-import.log
>index e800709d6a2170f8246bf8c84930b90e5d582eb4..42d1d760df0f5fe2c90ecbf9f298d98982a05a9e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -15,10 +15,8 @@ None
> ------------------------------------------------------------------------
> List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/allowany.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/array.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/attributes.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/callback.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/caller.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constants.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/constructor.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/dictionary-inherits.widl
>@@ -27,8 +25,6 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/documentation.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/enum.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/equivalent-decl.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception-inheritance.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/exception.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/extended-attributes.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/generic.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/getter-setter.widl
>@@ -38,9 +34,9 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/inherits-getter.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/interface-inherits.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterable.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/iterator.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/legacyiterable.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/maplike.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/mixin.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/namedconstructor.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/namespace.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/nointerfaceobject.widl
>@@ -51,13 +47,13 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/overridebuiltins.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/partial-interface.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/primitives.widl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/promise-void.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/prototyperoot.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/putforwards.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/record.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/reg-operations.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/replaceable.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/sequence.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/serializer.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/setlike.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/static.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier-attribute.widl
>@@ -65,7 +61,7 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/stringifier.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/treatasnull.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/treatasundefined.widl
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.idl
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef-union.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typedef.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/typesuffixes.widl
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/idl/uniontype.widl
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/allowany.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/allowany.json
>index 8abc7f9e09248acbe909c32eb007b10e75987339..2a93518ed9463776d3e7397074655a2aa9526af7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/allowany.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/allowany.json
>@@ -8,20 +8,19 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "g",
>+                "escapedName": "g",
>                 "arguments": [],
>                 "extAttrs": []
>             },
>@@ -29,34 +28,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "g",
>+                "escapedName": "g",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "B"
>+                            "idlType": "B",
>+                            "extAttrs": []
>                         },
>-                        "name": "b"
>+                        "name": "b",
>+                        "escapedName": "b"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -65,39 +65,42 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "g",
>+                "escapedName": "g",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [
>                             {
>                                 "name": "AllowAny",
>-                                "arguments": null
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>                             }
>                         ],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "s"
>+                        "name": "s",
>+                        "escapedName": "s"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -106,4 +109,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/array.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/array.json
>deleted file mode 100644
>index 39afaf6c8eb20192e60be96b962d2d641cf3998e..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/array.json
>+++ /dev/null
>@@ -1,34 +0,0 @@
>-[
>-    {
>-        "type": "interface",
>-        "name": "LotteryResults",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": 2,
>-                    "nullableArray": [false, false],
>-                    "union": false,
>-                    "idlType": "unsigned short"
>-                },
>-                "name": "numbers",
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": [
>-            {
>-                "name": "Constructor",
>-                "arguments": null
>-            }
>-        ]
>-    }
>-]
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/attributes.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/attributes.json
>index cdf46b0ecc20f4d4326e7fb9ad8e0384ac9dcb0e..f02cb2187a2af2d95d92135893ecdb97f91ba611 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/attributes.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/attributes.json
>@@ -1,37 +1,27 @@
> [
>     {
>-        "type": "exception",
>-        "name": "InvalidName",
>+        "type": "interface",
>+        "name": "Person",
>+        "partial": false,
>         "members": [
>             {
>-                "type": "field",
>-                "name": "reason",
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>+                "name": "age",
>+                "escapedName": "age",
>                 "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "exception",
>-        "name": "NoSuchPet",
>-        "members": [],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Person",
>-        "partial": false,
>-        "members": [
>+            },
>             {
>                 "type": "attribute",
>                 "static": false,
>@@ -39,18 +29,19 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>-                "name": "age",
>+                "name": "required",
>+                "escapedName": "required",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/callback.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/callback.json
>index 43a517510467c6666e69356b1f540b5da0f89f4c..89d63aae53d02a5f51dfcae4137fd3b9b1fe2c1d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/callback.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/callback.json
>@@ -3,27 +3,29 @@
>         "type": "callback",
>         "name": "AsyncOperationCallback",
>         "idlType": {
>-            "sequence": false,
>+            "type": "return-type",
>             "generic": null,
>             "nullable": false,
>-            "array": false,
>             "union": false,
>-            "idlType": "void"
>+            "idlType": "void",
>+            "extAttrs": []
>         },
>         "arguments": [
>             {
>                 "optional": false,
>                 "variadic": false,
>+                "default": null,
>                 "extAttrs": [],
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "argument-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>-                "name": "status"
>+                "name": "status",
>+                "escapedName": "status"
>             }
>         ],
>         "extAttrs": []
>@@ -37,34 +39,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "eventOccurred",
>+                "escapedName": "eventOccurred",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "details"
>+                        "name": "details",
>+                        "escapedName": "details"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -77,43 +80,47 @@
>         "type": "callback",
>         "name": "SortCallback",
>         "idlType": {
>-            "sequence": false,
>+            "type": "return-type",
>             "generic": null,
>             "nullable": false,
>-            "array": false,
>             "union": false,
>-            "idlType": "boolean"
>+            "idlType": "boolean",
>+            "extAttrs": []
>         },
>         "arguments": [
>             {
>                 "optional": false,
>                 "variadic": false,
>+                "default": null,
>                 "extAttrs": [],
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "argument-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "any"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>-                "name": "a"
>+                "name": "a",
>+                "escapedName": "a"
>             },
>             {
>                 "optional": false,
>                 "variadic": false,
>+                "default": null,
>                 "extAttrs": [],
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "argument-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "any"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>-                "name": "b"
>+                "name": "b",
>+                "escapedName": "b"
>             }
>         ],
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/caller.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/caller.json
>deleted file mode 100644
>index a0fb5e396a5a0e87721609c16e0e98eeaf362001..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/caller.json
>+++ /dev/null
>@@ -1,47 +0,0 @@
>-[
>-    {
>-        "type": "interface",
>-        "name": "NumberQuadrupler",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "operation",
>-                "getter": false,
>-                "setter": false,
>-                "creator": false,
>-                "deleter": false,
>-                "legacycaller": true,
>-                "static": false,
>-                "stringifier": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "float"
>-                },
>-                "name": "compute",
>-                "arguments": [
>-                    {
>-                        "optional": false,
>-                        "variadic": false,
>-                        "extAttrs": [],
>-                        "idlType": {
>-                            "sequence": false,
>-                            "generic": null,
>-                            "nullable": false,
>-                            "array": false,
>-                            "union": false,
>-                            "idlType": "float"
>-                        },
>-                        "name": "x"
>-                    }
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    }
>-]
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constants.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constants.json
>index 0fe6e92afc3a23571522d5a526c9f81ba538a74b..ef2b8c44ca167cf6eb866febb850062f2f456a75 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constants.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constants.json
>@@ -7,7 +7,14 @@
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "boolean",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>+                },
>                 "name": "DEBUG",
>                 "value": {
>                     "type": "boolean",
>@@ -18,51 +25,86 @@
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "short",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "short",
>+                    "extAttrs": []
>+                },
>                 "name": "negative",
>                 "value": {
>                     "type": "number",
>-                    "value": -1
>+                    "value": "-1"
>                 },
>                 "extAttrs": []
>             },
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "octet",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "octet",
>+                    "extAttrs": []
>+                },
>                 "name": "LF",
>                 "value": {
>                     "type": "number",
>-                    "value": 10
>+                    "value": "10"
>                 },
>                 "extAttrs": []
>             },
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "unsigned long",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>+                },
>                 "name": "BIT_MASK",
>                 "value": {
>                     "type": "number",
>-                    "value": 64512
>+                    "value": "0x0000fc00"
>                 },
>                 "extAttrs": []
>             },
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "float",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "float",
>+                    "extAttrs": []
>+                },
>                 "name": "AVOGADRO",
>                 "value": {
>                     "type": "number",
>-                    "value": 6.022e+23
>+                    "value": "6.022e23"
>                 },
>                 "extAttrs": []
>             },
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "unrestricted float",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "unrestricted float",
>+                    "extAttrs": []
>+                },
>                 "name": "sobig",
>                 "value": {
>                     "type": "Infinity",
>@@ -73,7 +115,14 @@
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "unrestricted double",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "unrestricted double",
>+                    "extAttrs": []
>+                },
>                 "name": "minusonedividedbyzero",
>                 "value": {
>                     "type": "Infinity",
>@@ -84,53 +133,17 @@
>             {
>                 "type": "const",
>                 "nullable": false,
>-                "idlType": "short",
>-                "name": "notanumber",
>-                "value": {
>-                    "type": "NaN"
>-                },
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "exception",
>-        "name": "Error",
>-        "members": [
>-            {
>-                "type": "const",
>-                "nullable": false,
>-                "idlType": "short",
>-                "name": "ERR_UNKNOWN",
>-                "value": {
>-                    "type": "number",
>-                    "value": 0
>-                },
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "const",
>-                "nullable": false,
>-                "idlType": "short",
>-                "name": "ERR_OUT_OF_MEMORY",
>-                "value": {
>-                    "type": "number",
>-                    "value": 1
>-                },
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "field",
>-                "name": "errorCode",
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "const-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "short"
>+                    "idlType": "short",
>+                    "extAttrs": []
>+                },
>+                "name": "notanumber",
>+                "value": {
>+                    "type": "NaN"
>                 },
>                 "extAttrs": []
>             }
>@@ -138,4 +151,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constructor.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constructor.json
>index e5944f32ee8671b13f86bed7b76a2a4d6c28bae8..efdd1b5a6bedc626b483a06d92260e57e37aceee 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constructor.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constructor.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "r",
>+                "escapedName": "r",
>                 "extAttrs": []
>             },
>             {
>@@ -28,14 +29,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "cx",
>+                "escapedName": "cx",
>                 "extAttrs": []
>             },
>             {
>@@ -45,14 +47,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "cy",
>+                "escapedName": "cy",
>                 "extAttrs": []
>             },
>             {
>@@ -62,14 +65,15 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "circumference",
>+                "escapedName": "circumference",
>                 "extAttrs": []
>             }
>         ],
>@@ -77,7 +81,9 @@
>         "extAttrs": [
>             {
>                 "name": "Constructor",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             },
>             {
>                 "name": "Constructor",
>@@ -85,19 +91,23 @@
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "radius"
>+                        "name": "radius",
>+                        "escapedName": "radius"
>                     }
>-                ]
>+                ],
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json
>index fbb2338a8df82cfa5beac24ab29e5fab73673525..595c35cf79748ac535a04d564bc8fe6377b5d728 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json
>@@ -7,14 +7,15 @@
>             {
>                 "type": "field",
>                 "name": "fillPattern",
>+                "escapedName": "fillPattern",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "extAttrs": [],
>                 "default": {
>@@ -25,14 +26,15 @@
>             {
>                 "type": "field",
>                 "name": "strokePattern",
>+                "escapedName": "strokePattern",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "extAttrs": [],
>                 "default": {
>@@ -42,16 +44,18 @@
>             {
>                 "type": "field",
>                 "name": "position",
>+                "escapedName": "position",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Point"
>+                    "idlType": "Point",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             }
>         ],
>         "inheritance": null,
>@@ -65,19 +69,21 @@
>             {
>                 "type": "field",
>                 "name": "hydrometry",
>+                "escapedName": "hydrometry",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             }
>         ],
>         "inheritance": "PaintOptions",
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary.json
>index a7c89caab23a3f88d748cbd91f497e788ad9c6bc..8bbc6b9dfabb4e55c309ff2ee31042823dcf963c 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary.json
>@@ -7,14 +7,15 @@
>             {
>                 "type": "field",
>                 "name": "fillPattern",
>+                "escapedName": "fillPattern",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "extAttrs": [],
>                 "default": {
>@@ -25,14 +26,15 @@
>             {
>                 "type": "field",
>                 "name": "strokePattern",
>+                "escapedName": "strokePattern",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "extAttrs": [],
>                 "default": {
>@@ -42,35 +44,38 @@
>             {
>                 "type": "field",
>                 "name": "position",
>+                "escapedName": "position",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Point"
>+                    "idlType": "Point",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             },
>             {
>                 "type": "field",
>                 "name": "seq",
>+                "escapedName": "seq",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": true,
>+                    "type": "dictionary-type",
>                     "generic": "sequence",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "dictionary-type",
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "long"
>-                    }
>+                        "idlType": "long",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "extAttrs": [],
>                 "default": {
>@@ -81,16 +86,18 @@
>             {
>                 "type": "field",
>                 "name": "reqSeq",
>+                "escapedName": "reqSeq",
>                 "required": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long"
>+                    "idlType": "long",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             }
>         ],
>         "inheritance": null,
>@@ -104,32 +111,36 @@
>             {
>                 "type": "field",
>                 "name": "h",
>+                "escapedName": "h",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long"
>+                    "idlType": "long",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             },
>             {
>                 "type": "field",
>                 "name": "d",
>+                "escapedName": "d",
>                 "required": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "dictionary-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long"
>+                    "idlType": "long",
>+                    "extAttrs": []
>                 },
>-                "extAttrs": []
>+                "extAttrs": [],
>+                "default": null
>             }
>         ],
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation-dos.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation-dos.json
>index 340e039b4495d7c93522046a4408ce5fad3e1da7..baa0b5a09b5ee17b95bcdd42dba4faba25cd3733 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation-dos.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation-dos.json
>@@ -7,4 +7,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation.json
>index 340e039b4495d7c93522046a4408ce5fad3e1da7..baa0b5a09b5ee17b95bcdd42dba4faba25cd3733 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/documentation.json
>@@ -7,4 +7,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/enum.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/enum.json
>index 196ee4e6405f27e19afeaca160c5c90afa78e54d..11f5d09f54b62b9eb14b5adae15822263d0ce738 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/enum.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/enum.json
>@@ -3,9 +3,18 @@
>         "type": "enum",
>         "name": "MealType",
>         "values": [
>-            "rice",
>-            "noodles",
>-            "other"
>+            {
>+                "type": "string",
>+                "value": "rice"
>+            },
>+            {
>+                "type": "string",
>+                "value": "noodles"
>+            },
>+            {
>+                "type": "string",
>+                "value": "other"
>+            }
>         ],
>         "extAttrs": []
>     },
>@@ -21,14 +30,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "MealType"
>+                    "idlType": "MealType",
>+                    "extAttrs": []
>                 },
>                 "name": "type",
>+                "escapedName": "type",
>                 "extAttrs": []
>             },
>             {
>@@ -38,62 +48,66 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "size",
>+                "escapedName": "size",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "initialize",
>+                "escapedName": "initialize",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "MealType"
>+                            "idlType": "MealType",
>+                            "extAttrs": []
>                         },
>-                        "name": "type"
>+                        "name": "type",
>+                        "escapedName": "type"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "size"
>+                        "name": "size",
>+                        "escapedName": "size"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -106,10 +120,19 @@
>         "type": "enum",
>         "name": "AltMealType",
>         "values": [
>-            "rice",
>-            "noodles",
>-            "other"
>+            {
>+                "type": "string",
>+                "value": "rice"
>+            },
>+            {
>+                "type": "string",
>+                "value": "noodles"
>+            },
>+            {
>+                "type": "string",
>+                "value": "other"
>+            }
>         ],
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json
>index 55a787fdcf08aa928188790abec2d236863dd53b..ee079a77790531666d214b67b58ea0d9f89e2f28 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json
>@@ -11,48 +11,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "propertyCount",
>+                "escapedName": "propertyCount",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "getProperty",
>+                "escapedName": "getProperty",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -61,48 +63,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": true,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "setProperty",
>+                "escapedName": "setProperty",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyValue"
>+                        "name": "propertyValue",
>+                        "escapedName": "propertyValue"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -113,7 +118,7 @@
>     },
>     {
>         "type": "interface",
>-        "name": "Dictionary",
>+        "name": "Dictionary2",
>         "partial": false,
>         "members": [
>             {
>@@ -123,48 +128,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "propertyCount",
>+                "escapedName": "propertyCount",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "getProperty",
>+                "escapedName": "getProperty",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -173,48 +180,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "setProperty",
>+                "escapedName": "setProperty",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyValue"
>+                        "name": "propertyValue",
>+                        "escapedName": "propertyValue"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -223,34 +233,35 @@
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -259,48 +270,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": true,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyValue"
>+                        "name": "propertyValue",
>+                        "escapedName": "propertyValue"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -309,4 +323,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json
>index f4dc68699a6d5d3d0fe83364764c92563d2d1a43..4a76b98285697e39b3b7a284bb20e8fa0a72c1ab 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json
>@@ -10,7 +10,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "unsigned short"
>                 },
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception.json
>deleted file mode 100644
>index 3f16de828ac8927be5a8d8dd5218c436c57bd266..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception.json
>+++ /dev/null
>@@ -1,35 +0,0 @@
>-[
>-    {
>-        "type": "interface",
>-        "name": "Dahut",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "type",
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "exception",
>-        "name": "SomeException",
>-        "members": [],
>-        "inheritance": null,
>-        "extAttrs": []
>-    }
>-]
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json
>index 3b5a3b2e22b31a9ddb322c07cfbd389df360a66b..25f56f0340ac8736b048fc2c48de87c2b37c6bd4 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json
>@@ -9,6 +9,7 @@
>             {
>                 "name": "Global",
>                 "arguments": null,
>+                "type": "extended-attribute",
>                 "rhs": {
>                     "type": "identifier-list",
>                     "value": [
>@@ -20,6 +21,7 @@
>             {
>                 "name": "Exposed",
>                 "arguments": null,
>+                "type": "extended-attribute",
>                 "rhs": {
>                     "type": "identifier",
>                     "value": "ServiceWorker"
>@@ -28,36 +30,211 @@
>         ]
>     },
>     {
>-      "type": "interface",
>-      "name": "IdInterface",
>-      "partial": false,
>-      "members": [],
>-      "inheritance": null,
>-      "extAttrs": [
>-        {
>-          "name": "IntAttr",
>-          "arguments": null,
>-          "rhs": {
>-            "type": "integer",
>-            "value": "0"
>-          }
>-        },
>-        {
>-          "name": "FloatAttr",
>-          "arguments": null,
>-          "rhs": {
>-            "type": "float",
>-            "value": "3.14"
>-          }
>-        },
>-        {
>-          "name": "StringAttr",
>-          "arguments": null,
>-          "rhs": {
>-            "type": "string",
>-            "value": "\"abc\""
>-          }
>-        }
>-      ]
>+        "type": "interface",
>+        "name": "IdInterface",
>+        "partial": false,
>+        "members": [],
>+        "inheritance": null,
>+        "extAttrs": [
>+            {
>+                "name": "IntAttr",
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": {
>+                    "type": "integer",
>+                    "value": "0"
>+                }
>+            },
>+            {
>+                "name": "FloatAttr",
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": {
>+                    "type": "float",
>+                    "value": "3.14"
>+                }
>+            },
>+            {
>+                "name": "StringAttr",
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": {
>+                    "type": "string",
>+                    "value": "\"abc\""
>+                }
>+            }
>+        ]
>+    },
>+    {
>+        "type": "interface",
>+        "name": "Circle",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "double",
>+                    "extAttrs": []
>+                },
>+                "name": "r",
>+                "escapedName": "r",
>+                "extAttrs": []
>+            },
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "double",
>+                    "extAttrs": []
>+                },
>+                "name": "cx",
>+                "escapedName": "cx",
>+                "extAttrs": []
>+            },
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "double",
>+                    "extAttrs": []
>+                },
>+                "name": "cy",
>+                "escapedName": "cy",
>+                "extAttrs": []
>+            },
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": true,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "double",
>+                    "extAttrs": []
>+                },
>+                "name": "circumference",
>+                "escapedName": "circumference",
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": [
>+            {
>+                "name": "Constructor",
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>+            },
>+            {
>+                "name": "Constructor",
>+                "arguments": [
>+                    {
>+                        "optional": false,
>+                        "variadic": false,
>+                        "default": null,
>+                        "extAttrs": [],
>+                        "idlType": {
>+                            "type": "argument-type",
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "double",
>+                            "extAttrs": []
>+                        },
>+                        "name": "radius",
>+                        "escapedName": "radius"
>+                    }
>+                ],
>+                "type": "extended-attribute",
>+                "rhs": null
>+            }
>+        ]
>+    },
>+    {
>+        "type": "interface",
>+        "name": "I",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": true,
>+                    "idlType": [
>+                        {
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "long",
>+                            "extAttrs": []
>+                        },
>+                        {
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "Node",
>+                            "extAttrs": []
>+                        }
>+                    ],
>+                    "extAttrs": [
>+                        {
>+                            "name": "XAttr",
>+                            "arguments": null,
>+                            "type": "extended-attribute",
>+                            "rhs": null
>+                        }
>+                    ]
>+                },
>+                "name": "attrib",
>+                "escapedName": "attrib",
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": [
>+            {
>+                "name": "Exposed",
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": {
>+                    "type": "identifier",
>+                    "value": "Window"
>+                }
>+            }
>+        ]
>     }
> ]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/generic.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/generic.json
>index e39654ffdb2131fd0260e1a6264dbf48f74945b9..d3c26ac7cd0ddd9eb167d7a5ea9891f82fb06d5b 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/generic.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/generic.json
>@@ -8,41 +8,40 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": "Promise",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>-                        "generic": "ResponsePromise",
>+                        "type": "return-type",
>+                        "generic": "Promise",
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>                         "idlType": {
>-                            "sequence": true,
>+                            "type": "return-type",
>                             "generic": "sequence",
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": {
>-                                "sequence": false,
>+                                "type": "return-type",
>                                 "generic": null,
>                                 "nullable": true,
>-                                "array": false,
>                                 "union": false,
>-                                "idlType": "DOMString"
>-                            }
>-                        }
>-                    }
>+                                "idlType": "DOMString",
>+                                "extAttrs": []
>+                            },
>+                            "extAttrs": []
>+                        },
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "bar",
>+                "escapedName": "bar",
>                 "arguments": [],
>                 "extAttrs": []
>             },
>@@ -53,22 +52,22 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": "Promise",
>                     "nullable": false,
>-                    "array": 1,
>-                    "nullableArray": [false],
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "attribute-type",
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "DOMString"
>-                    }
>+                        "idlType": "DOMString",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "baz",
>+                "escapedName": "baz",
>                 "extAttrs": []
>             }
>         ],
>@@ -84,28 +83,26 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": "Promise",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "return-type",
>                         "generic": null,
>                         "nullable": true,
>-                        "nullableArray": [false],
>-                        "array": 1,
>                         "union": false,
>-                        "idlType": "Client"
>-                    }
>+                        "idlType": "Client",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "getServiced",
>+                "escapedName": "getServiced",
>                 "arguments": [],
>                 "extAttrs": []
>             },
>@@ -113,27 +110,26 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": "Promise",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "return-type",
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "any"
>-                    }
>+                        "idlType": "any",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "reloadAll",
>+                "escapedName": "reloadAll",
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -150,27 +146,26 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>-                    "generic": "ResponsePromise",
>+                    "type": "return-type",
>+                    "generic": "Promise",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "return-type",
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "any"
>-                    }
>+                        "idlType": "any",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "default",
>+                "escapedName": "default",
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -178,4 +173,4 @@
>         "inheritance": "Event",
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json
>index 94d20d594db15e5e2e15403930c2bd1e32a28b33..6f8196fe56dd3d04e9f64f719c82c552193320d8 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json
>@@ -11,48 +11,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "propertyCount",
>+                "escapedName": "propertyCount",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -61,48 +63,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": true,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyName"
>+                        "name": "propertyName",
>+                        "escapedName": "propertyName"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "propertyValue"
>+                        "name": "propertyValue",
>+                        "escapedName": "propertyValue"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -111,4 +116,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/identifier-qualified-names.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/identifier-qualified-names.json
>index d87ea3b5f369db698e93072a1b76562a16d50fec..098cdcb1fbbc4f140f6aadaa7ee2977b2fccd4b9 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/identifier-qualified-names.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/identifier-qualified-names.json
>@@ -2,48 +2,16 @@
>     {
>         "type": "typedef",
>         "idlType": {
>-            "sequence": false,
>+            "type": "typedef-type",
>             "generic": null,
>             "nullable": false,
>-            "array": false,
>             "union": false,
>-            "idlType": "float"
>+            "idlType": "float",
>+            "extAttrs": []
>         },
>         "name": "number",
>         "extAttrs": []
>     },
>-    {
>-        "type": "exception",
>-        "name": "FrameworkException",
>-        "members": [
>-            {
>-                "type": "const",
>-                "nullable": false,
>-                "idlType": "long",
>-                "name": "ERR_NOT_FOUND",
>-                "value": {
>-                    "type": "number",
>-                    "value": 1
>-                },
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "field",
>-                "name": "code",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "long"
>-                },
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>     {
>         "type": "interface",
>         "name": "System",
>@@ -53,34 +21,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "object"
>+                    "idlType": "object",
>+                    "extAttrs": []
>                 },
>                 "name": "createObject",
>+                "escapedName": "createObject",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "interface"
>+                        "name": "interface",
>+                        "escapedName": "_interface"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -89,34 +58,35 @@
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "keyName"
>+                        "name": "keyName",
>+                        "escapedName": "keyName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -137,14 +107,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "const",
>+                "escapedName": "_const",
>                 "extAttrs": []
>             },
>             {
>@@ -154,14 +125,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "value",
>+                "escapedName": "_value",
>                 "extAttrs": []
>             }
>         ],
>@@ -170,41 +142,42 @@
>     },
>     {
>         "type": "interface",
>-        "name": "Foo",
>+        "name": "FooEventTarget",
>         "partial": false,
>         "members": [
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>-                "name": "op",
>+                "name": "addEventListener",
>+                "escapedName": "addEventListener",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>-                            "nullable": false,
>-                            "array": false,
>+                            "nullable": true,
>                             "union": false,
>-                            "idlType": "object"
>+                            "idlType": "EventListener",
>+                            "extAttrs": []
>                         },
>-                        "name": "interface"
>+                        "name": "callback",
>+                        "escapedName": "callback"
>                     }
>                 ],
>                 "extAttrs": []
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/implements.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/implements.json
>index fa00e3374267b93b9d56b2ddc8b0b35e7302f481..1736118cd902fb6af5ebca4eba656ffb51bff28b 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/implements.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/implements.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>                 "name": "nodeType",
>+                "escapedName": "nodeType",
>                 "extAttrs": []
>             }
>         ],
>@@ -34,62 +35,67 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "addEventListener",
>+                "escapedName": "addEventListener",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "type"
>+                        "name": "type",
>+                        "escapedName": "type"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "EventListener"
>+                            "idlType": "EventListener",
>+                            "extAttrs": []
>                         },
>-                        "name": "listener"
>+                        "name": "listener",
>+                        "escapedName": "listener"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "boolean"
>+                            "idlType": "boolean",
>+                            "extAttrs": []
>                         },
>-                        "name": "useCapture"
>+                        "name": "useCapture",
>+                        "escapedName": "useCapture"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -104,4 +110,4 @@
>         "implements": "EventTarget",
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/indexed-properties.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/indexed-properties.json
>index 23cc4ab1023c2fedd4dab6c640a2b1307bc800af..dccd511af96bfd6e90d2b6829d823fabbf8c6d94 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/indexed-properties.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/indexed-properties.json
>@@ -11,48 +11,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "size",
>+                "escapedName": "size",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "any"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>                 "name": "getByIndex",
>+                "escapedName": "getByIndex",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "index"
>+                        "name": "index",
>+                        "escapedName": "index"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -61,48 +63,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": true,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "setByIndex",
>+                "escapedName": "setByIndex",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "index"
>+                        "name": "index",
>+                        "escapedName": "index"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "any"
>+                            "idlType": "any",
>+                            "extAttrs": []
>                         },
>-                        "name": "value"
>+                        "name": "value",
>+                        "escapedName": "value"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -111,34 +116,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": true,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "removeByIndex",
>+                "escapedName": "removeByIndex",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "index"
>+                        "name": "index",
>+                        "escapedName": "index"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -147,34 +153,35 @@
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "any"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>                 "name": "get",
>+                "escapedName": "get",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "name"
>+                        "name": "name",
>+                        "escapedName": "name"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -183,48 +190,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": true,
>-                "creator": true,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "set",
>+                "escapedName": "set",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "name"
>+                        "name": "name",
>+                        "escapedName": "name"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "any"
>+                            "idlType": "any",
>+                            "extAttrs": []
>                         },
>-                        "name": "value"
>+                        "name": "value",
>+                        "escapedName": "value"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -233,34 +243,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": true,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "remove",
>+                "escapedName": "remove",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "name"
>+                        "name": "name",
>+                        "escapedName": "name"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -269,4 +280,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/inherits-getter.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/inherits-getter.json
>index 468e3caef711f3afab68a785805dd75f74f96ab9..86eb68e270e46a9c5ab56456c3610d523bcdaeb9 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/inherits-getter.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/inherits-getter.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             }
>         ],
>@@ -37,14 +38,15 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>                 "name": "age",
>+                "escapedName": "age",
>                 "extAttrs": []
>             },
>             {
>@@ -54,18 +56,46 @@
>                 "inherit": true,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": "Animal",
>         "extAttrs": []
>+    },
>+    {
>+        "type": "interface",
>+        "name": "Ghost",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": true,
>+                "readonly": true,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>+                },
>+                "name": "name",
>+                "escapedName": "name",
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": "Person",
>+        "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/interface-inherits.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/interface-inherits.json
>index eee07cd1dec7bb6e3691fb207a0ca45ead4a310d..02caf35f605ab376cee42c8b5e981d1ca18772c1 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/interface-inherits.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/interface-inherits.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             }
>         ],
>@@ -37,14 +38,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Dog"
>+                    "idlType": "Dog",
>+                    "extAttrs": []
>                 },
>                 "name": "pet",
>+                "escapedName": "pet",
>                 "extAttrs": []
>             }
>         ],
>@@ -63,18 +65,19 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Human"
>+                    "idlType": "Human",
>+                    "extAttrs": []
>                 },
>                 "name": "owner",
>+                "escapedName": "owner",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": "Animal",
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterable.json
>index 3e38991dd9db21c92bc2b50769ff8b87247dacef..ee906f75ea2eb5f7a3aef33c53a7e03443b6f450 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterable.json
>@@ -6,14 +6,16 @@
>         "members": [
>             {
>                 "type": "iterable",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "long"
>-                },
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": []
>+                    }
>+                ],
>                 "extAttrs": []
>             }
>         ],
>@@ -29,20 +31,50 @@
>                 "type": "iterable",
>                 "idlType": [
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "short"
>+                        "idlType": "short",
>+                        "extAttrs": []
>                     },
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": true,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "double"
>+                        "idlType": "double",
>+                        "extAttrs": []
>+                    }
>+                ],
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>+    },
>+    {
>+        "type": "interface",
>+        "name": "IterableThree",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "iterable",
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": [
>+                            {
>+                                "name": "XAttr",
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>+                            }
>+                        ]
>                     }
>                 ],
>                 "extAttrs": []
>@@ -52,4 +84,3 @@
>         "extAttrs": []
>     }
> ]
>-
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterator.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterator.json
>index cc3c9ec505d8e39b249121a3acdb33ea555f08d6..f9605b83450cb5dcd21ec338b82796a2a2304b08 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterator.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterator.json
>@@ -8,16 +8,13 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Session"
>                 },
>@@ -31,7 +28,6 @@
>                             "sequence": false,
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": "DOMString"
>                         },
>@@ -50,7 +46,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "unsigned long"
>                 },
>@@ -61,16 +56,13 @@
>                 "type": "iterator",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Session"
>                 },
>@@ -95,7 +87,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "DOMString"
>                 },
>@@ -115,16 +106,13 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Session2"
>                 },
>@@ -138,7 +126,6 @@
>                             "sequence": false,
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": "DOMString"
>                         },
>@@ -157,7 +144,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "unsigned long"
>                 },
>@@ -168,16 +154,13 @@
>                 "type": "iterator",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Session2"
>                 },
>@@ -203,7 +186,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "DOMString"
>                 },
>@@ -229,7 +211,6 @@
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "unsigned long"
>                 },
>@@ -249,16 +230,13 @@
>                 "type": "iterator",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Node"
>                 },
>@@ -278,16 +256,13 @@
>                 "type": "iterator",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>                     "sequence": false,
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": "Node"
>                 },
>@@ -298,4 +273,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json
>index e63f99de43f43d2170867185971bd49e2b5f5587..80fd000a84937162deb765f585e4bdd24dc83ebe 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json
>@@ -6,14 +6,16 @@
>         "members": [
>             {
>                 "type": "legacyiterable",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "long"
>-                },
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": []
>+                    }
>+                ],
>                 "extAttrs": []
>             }
>         ],
>@@ -21,4 +23,3 @@
>         "extAttrs": []
>     }
> ]
>-
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/maplike.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/maplike.json
>index 017d8b3f3ec2c406b25ebf904737458f8f6d1174..2cb8c360ee3e2f03fe400307bbf757b4458af887 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/maplike.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/maplike.json
>@@ -8,20 +8,20 @@
>                 "type": "maplike",
>                 "idlType": [
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "long"
>+                        "idlType": "long",
>+                        "extAttrs": []
>                     },
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "float"
>+                        "idlType": "float",
>+                        "extAttrs": []
>                     }
>                 ],
>                 "readonly": false,
>@@ -40,20 +40,20 @@
>                 "type": "maplike",
>                 "idlType": [
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "long"
>+                        "idlType": "long",
>+                        "extAttrs": []
>                     },
>                     {
>-                        "sequence": false,
>+                        "type": null,
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "float"
>+                        "idlType": "float",
>+                        "extAttrs": []
>                     }
>                 ],
>                 "readonly": true,
>@@ -62,6 +62,51 @@
>         ],
>         "inheritance": null,
>         "extAttrs": []
>+    },
>+    {
>+        "type": "interface",
>+        "name": "I",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "maplike",
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "DOMString",
>+                        "extAttrs": [
>+                            {
>+                                "name": "XAttr2",
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>+                            }
>+                        ]
>+                    },
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": [
>+                            {
>+                                "name": "XAttr3",
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>+                            }
>+                        ]
>+                    }
>+                ],
>+                "readonly": false,
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>     }
> ]
>-
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/mixin.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/mixin.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..b037cb3577941adf5c591b2d2e9312ebd6d77f02
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/mixin.json
>@@ -0,0 +1,66 @@
>+[
>+    {
>+        "type": "interface mixin",
>+        "name": "GlobalCrypto",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": true,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "Crypto",
>+                    "extAttrs": []
>+                },
>+                "name": "crypto",
>+                "escapedName": "crypto",
>+                "extAttrs": []
>+            }
>+        ],
>+        "extAttrs": []
>+    },
>+    {
>+        "type": "includes",
>+        "target": "Window",
>+        "includes": "GlobalCrypto",
>+        "extAttrs": []
>+    },
>+    {
>+        "type": "includes",
>+        "target": "WorkerGlobalScope",
>+        "includes": "GlobalCrypto",
>+        "extAttrs": []
>+    },
>+    {
>+        "type": "interface mixin",
>+        "name": "WindowOrWorkerGlobalScope",
>+        "partial": true,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": true,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "Crypto",
>+                    "extAttrs": []
>+                },
>+                "name": "crypto",
>+                "escapedName": "crypto",
>+                "extAttrs": []
>+            }
>+        ],
>+        "extAttrs": []
>+    }
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json
>index a947a64a4e2e3c050a4ad154826282f3b4a5fb33..deb429e986eb106e958e799048f6b4ce2da1df51 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json
>@@ -9,6 +9,7 @@
>             {
>                 "name": "NamedConstructor",
>                 "arguments": null,
>+                "type": "extended-attribute",
>                 "rhs": {
>                     "type": "identifier",
>                     "value": "Audio"
>@@ -20,18 +21,21 @@
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "src"
>+                        "name": "src",
>+                        "escapedName": "src"
>                     }
>                 ],
>+                "type": "extended-attribute",
>                 "rhs": {
>                     "type": "identifier",
>                     "value": "Audio"
>@@ -39,4 +43,4 @@
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namespace.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namespace.json
>index 7c7ba771e1bf3ade1dc128e38a8d8bdbf02702b6..9e37b26fa6504f9862877c25c97e94893dc8d833 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namespace.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namespace.json
>@@ -11,62 +11,66 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Vector"
>+                    "idlType": "Vector",
>+                    "extAttrs": []
>                 },
>                 "name": "unit",
>+                "escapedName": "unit",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "double"
>+                    "idlType": "double",
>+                    "extAttrs": []
>                 },
>                 "name": "dotProduct",
>+                "escapedName": "dotProduct",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Vector"
>+                            "idlType": "Vector",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Vector"
>+                            "idlType": "Vector",
>+                            "extAttrs": []
>                         },
>-                        "name": "y"
>+                        "name": "y",
>+                        "escapedName": "y"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -75,48 +79,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Vector"
>+                    "idlType": "Vector",
>+                    "extAttrs": []
>                 },
>                 "name": "crossProduct",
>+                "escapedName": "crossProduct",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Vector"
>+                            "idlType": "Vector",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Vector"
>+                            "idlType": "Vector",
>+                            "extAttrs": []
>                         },
>-                        "name": "y"
>+                        "name": "y",
>+                        "escapedName": "y"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -131,4 +138,4 @@
>         "members": [],
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json
>index 90f0d63c82e3f25d7f097b2f0f4cd1b0899fb1dc..cafb5e0e156bd0b6e90f37f94bc551a9937f5e40 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json
>@@ -8,34 +8,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "any"
>+                    "idlType": "any",
>+                    "extAttrs": []
>                 },
>                 "name": "lookupEntry",
>+                "escapedName": "lookupEntry",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "key"
>+                        "name": "key",
>+                        "escapedName": "key"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -45,8 +46,10 @@
>         "extAttrs": [
>             {
>                 "name": "NoInterfaceObject",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullable.json
>index 300442f0d4661722e18af8f1e7b97940e92afe64..f325e2eab7b8af6c102c941d686f14411915c5c1 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullable.json
>@@ -7,7 +7,14 @@
>             {
>                 "type": "const",
>                 "nullable": true,
>-                "idlType": "boolean",
>+                "idlType": {
>+                    "type": "const-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>+                },
>                 "name": "ARE_WE_THERE_YET",
>                 "value": {
>                     "type": "boolean",
>@@ -31,18 +38,19 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "namespaceURI",
>+                "escapedName": "namespaceURI",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullableobjects.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullableobjects.json
>index 40f7db0c1c9c8c435eb216205b239959995548a2..27ecd25d363bfb39524327d09e0f8ca6c0a56788 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullableobjects.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nullableobjects.json
>@@ -24,34 +24,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": true,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "A"
>+                            "idlType": "A",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -60,34 +61,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": true,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "B"
>+                            "idlType": "B",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -96,4 +98,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/operation-optional-arg.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/operation-optional-arg.json
>index 6ca32576b7a41f81dcddfb7eb462508eae5d91a5..4b7436ba5baf7601936b34050e71191a47812c6b 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/operation-optional-arg.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/operation-optional-arg.json
>@@ -8,80 +8,86 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "object"
>+                    "idlType": "object",
>+                    "extAttrs": []
>                 },
>                 "name": "createColor",
>+                "escapedName": "createColor",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "v1"
>+                        "name": "v1",
>+                        "escapedName": "v1"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "v2"
>+                        "name": "v2",
>+                        "escapedName": "v2"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "v3"
>+                        "name": "v3",
>+                        "escapedName": "v3"
>                     },
>                     {
>                         "optional": true,
>                         "variadic": false,
>+                        "default": {
>+                            "type": "number",
>+                            "value": "3.5"
>+                        },
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>                         "name": "alpha",
>-                        "default": {
>-                            "type": "number",
>-                            "value": 3.5
>-                        }
>+                        "escapedName": "alpha"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -90,4 +96,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overloading.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overloading.json
>index c3baa439623b09bfdb6a71b571a621a12a2e6dc5..bf7aca6cde3808e7ed3616407f7dc49fa631b769 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overloading.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overloading.json
>@@ -24,34 +24,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "A"
>+                            "idlType": "A",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -60,34 +61,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "B"
>+                            "idlType": "B",
>+                            "extAttrs": []
>                         },
>-                        "name": "x"
>+                        "name": "x",
>+                        "escapedName": "x"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -98,41 +100,42 @@
>     },
>     {
>         "type": "interface",
>-        "name": "A",
>+        "name": "D",
>         "partial": false,
>         "members": [
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "a"
>+                        "name": "a",
>+                        "escapedName": "a"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -141,67 +144,74 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [
>                             {
>                                 "name": "AllowAny",
>-                                "arguments": null
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>                             }
>                         ],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "a"
>+                        "name": "a",
>+                        "escapedName": "a"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "b"
>+                        "name": "b",
>+                        "escapedName": "b"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": true,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "c"
>+                        "name": "c",
>+                        "escapedName": "c"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -210,20 +220,19 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [],
>                 "extAttrs": []
>             },
>@@ -231,76 +240,83 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "f",
>+                "escapedName": "f",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "long"
>+                            "idlType": "long",
>+                            "extAttrs": []
>                         },
>-                        "name": "a"
>+                        "name": "a",
>+                        "escapedName": "a"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "b"
>+                        "name": "b",
>+                        "escapedName": "b"
>                     },
>                     {
>                         "optional": true,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "c"
>+                        "name": "c",
>+                        "escapedName": "c"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": true,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "float"
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>-                        "name": "d"
>+                        "name": "d",
>+                        "escapedName": "d"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -309,4 +325,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json
>index 9e2f795e2ae175fd31eb891bd07df595cc4e7cd9..e54a468eb98e867ed8b0d68a9c75dcfbd763e98f 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json
>@@ -11,48 +11,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "length",
>+                "escapedName": "length",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": true,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "lookup",
>+                "escapedName": "lookup",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "key"
>+                        "name": "key",
>+                        "escapedName": "key"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -62,8 +64,10 @@
>         "extAttrs": [
>             {
>                 "name": "OverrideBuiltins",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json
>index 53c65a453bd7301863ed0fae935a10eb2aa7360f..d791262f465691ebd7aeab9118d48475c3230a0c 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "bar",
>+                "escapedName": "bar",
>                 "extAttrs": []
>             }
>         ],
>@@ -37,17 +38,18 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "quux",
>+                "escapedName": "quux",
>                 "extAttrs": []
>             }
>         ],
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/primitives.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/primitives.json
>index 7160c2a4ce066df3284c50eaf4f4af80ef01ab90..a216221140c65aec9d7878ef0a96a8f02fe0ea60 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/primitives.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/primitives.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "truth",
>+                "escapedName": "truth",
>                 "extAttrs": []
>             },
>             {
>@@ -28,14 +29,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "byte"
>+                    "idlType": "byte",
>+                    "extAttrs": []
>                 },
>                 "name": "character",
>+                "escapedName": "character",
>                 "extAttrs": []
>             },
>             {
>@@ -45,14 +47,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "octet"
>+                    "idlType": "octet",
>+                    "extAttrs": []
>                 },
>                 "name": "value",
>+                "escapedName": "value",
>                 "extAttrs": []
>             },
>             {
>@@ -62,14 +65,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "short"
>+                    "idlType": "short",
>+                    "extAttrs": []
>                 },
>                 "name": "number",
>+                "escapedName": "number",
>                 "extAttrs": []
>             },
>             {
>@@ -79,14 +83,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>                 "name": "positive",
>+                "escapedName": "positive",
>                 "extAttrs": []
>             },
>             {
>@@ -96,14 +101,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long"
>+                    "idlType": "long",
>+                    "extAttrs": []
>                 },
>                 "name": "big",
>+                "escapedName": "big",
>                 "extAttrs": []
>             },
>             {
>@@ -113,14 +119,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "bigpositive",
>+                "escapedName": "bigpositive",
>                 "extAttrs": []
>             },
>             {
>@@ -130,14 +137,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long long"
>+                    "idlType": "long long",
>+                    "extAttrs": []
>                 },
>                 "name": "bigbig",
>+                "escapedName": "bigbig",
>                 "extAttrs": []
>             },
>             {
>@@ -147,14 +155,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long long"
>+                    "idlType": "unsigned long long",
>+                    "extAttrs": []
>                 },
>                 "name": "bigbigpositive",
>+                "escapedName": "bigbigpositive",
>                 "extAttrs": []
>             },
>             {
>@@ -164,14 +173,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "real",
>+                "escapedName": "real",
>                 "extAttrs": []
>             },
>             {
>@@ -181,14 +191,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "double"
>+                    "idlType": "double",
>+                    "extAttrs": []
>                 },
>                 "name": "bigreal",
>+                "escapedName": "bigreal",
>                 "extAttrs": []
>             },
>             {
>@@ -198,14 +209,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unrestricted float"
>+                    "idlType": "unrestricted float",
>+                    "extAttrs": []
>                 },
>                 "name": "realwithinfinity",
>+                "escapedName": "realwithinfinity",
>                 "extAttrs": []
>             },
>             {
>@@ -215,14 +227,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unrestricted double"
>+                    "idlType": "unrestricted double",
>+                    "extAttrs": []
>                 },
>                 "name": "bigrealwithinfinity",
>+                "escapedName": "bigrealwithinfinity",
>                 "extAttrs": []
>             },
>             {
>@@ -232,14 +245,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "string",
>+                "escapedName": "string",
>                 "extAttrs": []
>             },
>             {
>@@ -249,14 +263,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "ByteString"
>+                    "idlType": "ByteString",
>+                    "extAttrs": []
>                 },
>                 "name": "bytes",
>+                "escapedName": "bytes",
>                 "extAttrs": []
>             },
>             {
>@@ -266,14 +281,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Date"
>+                    "idlType": "Date",
>+                    "extAttrs": []
>                 },
>                 "name": "date",
>+                "escapedName": "date",
>                 "extAttrs": []
>             },
>             {
>@@ -283,18 +299,19 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "RegExp"
>+                    "idlType": "RegExp",
>+                    "extAttrs": []
>                 },
>                 "name": "regexp",
>+                "escapedName": "regexp",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/promise-void.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/promise-void.json
>new file mode 100644
>index 0000000000000000000000000000000000000000..7676838b8179d9e736a8f36b97628bece12a84d8
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/promise-void.json
>@@ -0,0 +1,36 @@
>+[
>+    {
>+        "type": "interface",
>+        "name": "Cat",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": "Promise",
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": {
>+                        "type": "return-type",
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "void",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>+                },
>+                "name": "meow",
>+                "escapedName": "meow",
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>+    }
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json
>index 666798d94cfd272ca349d7ba549512025d4aa4f0..cec79ff66b6a49dc39def76c4252d87e96a2ce28 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>                 "name": "nodeType",
>+                "escapedName": "nodeType",
>                 "extAttrs": []
>             }
>         ],
>@@ -26,8 +27,10 @@
>         "extAttrs": [
>             {
>                 "name": "PrototypeRoot",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json
>index bd5e619cac553463e125d2489b4b282e46563ae8..951b3ef718ccc90c7cee3ff035aca61e61396898 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json
>@@ -11,18 +11,20 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Name"
>+                    "idlType": "Name",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": [
>                     {
>                         "name": "PutForwards",
>                         "arguments": null,
>+                        "type": "extended-attribute",
>                         "rhs": {
>                             "type": "identifier",
>                             "value": "full"
>@@ -37,18 +39,19 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned short"
>+                    "idlType": "unsigned short",
>+                    "extAttrs": []
>                 },
>                 "name": "age",
>+                "escapedName": "age",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/record.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/record.json
>index d2a21a4acd99936119cd7d8a6757e361c83141cc..1be5427c74d6c83b429273443fefb03263d0f98f 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/record.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/record.json
>@@ -8,58 +8,59 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "foo",
>+                "escapedName": "foo",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": true,
>+                            "type": "argument-type",
>                             "generic": "sequence",
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": {
>-                                "sequence": false,
>+                                "type": "argument-type",
>                                 "generic": "record",
>                                 "nullable": false,
>-                                "array": false,
>                                 "union": false,
>                                 "idlType": [
>                                     {
>-                                        "sequence": false,
>+                                        "type": "argument-type",
>                                         "generic": null,
>                                         "nullable": false,
>-                                        "array": false,
>                                         "union": false,
>-                                        "idlType": "ByteString"
>+                                        "idlType": "ByteString",
>+                                        "extAttrs": []
>                                     },
>                                     {
>-                                        "sequence": false,
>+                                        "type": "argument-type",
>                                         "generic": null,
>                                         "nullable": false,
>-                                        "array": false,
>                                         "union": false,
>-                                        "idlType": "any"
>+                                        "idlType": "any",
>+                                        "extAttrs": []
>                                     }
>-                                ]
>-                            }
>+                                ],
>+                                "extAttrs": []
>+                            },
>+                            "extAttrs": []
>                         },
>-                        "name": "param"
>+                        "name": "param",
>+                        "escapedName": "param"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -68,75 +69,53 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": "record",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": [
>                         {
>-                            "sequence": false,
>+                            "type": "return-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>                         {
>-                            "sequence": false,
>+                            "type": "return-type",
>                             "generic": null,
>                             "nullable": true,
>-                            "array": false,
>                             "union": true,
>                             "idlType": [
>                                 {
>-                                    "sequence": false,
>+                                    "type": null,
>                                     "generic": null,
>                                     "nullable": false,
>-                                    "array": false,
>                                     "union": false,
>-                                    "idlType": "float"
>+                                    "idlType": "float",
>+                                    "extAttrs": []
>                                 },
>                                 {
>-                                    "sequence": false,
>+                                    "type": null,
>                                     "generic": null,
>                                     "nullable": false,
>-                                    "array": false,
>                                     "union": false,
>-                                    "idlType": "DOMString"
>+                                    "idlType": "DOMString",
>+                                    "extAttrs": []
>                                 }
>-                            ]
>+                            ],
>+                            "extAttrs": []
>                         }
>-                    ]
>+                    ],
>+                    "extAttrs": []
>                 },
>                 "name": "bar",
>-                "arguments": [],
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "operation",
>-                "getter": false,
>-                "setter": false,
>-                "creator": false,
>-                "deleter": false,
>-                "legacycaller": false,
>-                "static": false,
>-                "stringifier": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "record"
>-                },
>-                "name": "baz",
>+                "escapedName": "bar",
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -149,36 +128,93 @@
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": "record",
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": [
>                                 {
>-                                    "sequence": false,
>+                                    "type": "argument-type",
>                                     "generic": null,
>                                     "nullable": false,
>-                                    "array": false,
>                                     "union": false,
>-                                    "idlType": "USVString"
>+                                    "idlType": "USVString",
>+                                    "extAttrs": []
>                                 },
>                                 {
>-                                    "sequence": false,
>+                                    "type": "argument-type",
>                                     "generic": null,
>                                     "nullable": false,
>-                                    "array": false,
>                                     "union": false,
>-                                    "idlType": "USVString"
>+                                    "idlType": "USVString",
>+                                    "extAttrs": []
>                                 }
>-                            ]
>+                            ],
>+                            "extAttrs": []
>                         },
>-                        "name": "init"
>+                        "name": "init",
>+                        "escapedName": "init"
>                     }
>-                ]
>+                ],
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>+    },
>+    {
>+        "type": "interface",
>+        "name": "Bar",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "operation",
>+                "getter": false,
>+                "setter": false,
>+                "deleter": false,
>+                "static": false,
>+                "stringifier": false,
>+                "idlType": {
>+                    "type": "return-type",
>+                    "generic": "record",
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": [
>+                        {
>+                            "type": "return-type",
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>+                        },
>+                        {
>+                            "type": "return-type",
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "float",
>+                            "extAttrs": [
>+                                {
>+                                    "name": "XAttr",
>+                                    "arguments": null,
>+                                    "type": "extended-attribute",
>+                                    "rhs": null
>+                                }
>+                            ]
>+                        }
>+                    ],
>+                    "extAttrs": []
>+                },
>+                "name": "bar",
>+                "escapedName": "bar",
>+                "arguments": [],
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>     }
> ]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json
>index c827fff03b6bf3bb4357d1aeee4170345e61437e..8795c59ec87371e74bf7597861478ab8b1c15b54 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "width",
>+                "escapedName": "width",
>                 "extAttrs": []
>             },
>             {
>@@ -28,27 +29,21 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "height",
>+                "escapedName": "height",
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>     },
>-    {
>-        "type": "exception",
>-        "name": "NoPointerDevice",
>-        "members": [],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>     {
>         "type": "interface",
>         "name": "Button",
>@@ -58,20 +53,19 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "isMouseOver",
>+                "escapedName": "isMouseOver",
>                 "arguments": [],
>                 "extAttrs": []
>             },
>@@ -79,34 +73,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "setDimensions",
>+                "escapedName": "setDimensions",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Dimensions"
>+                            "idlType": "Dimensions",
>+                            "extAttrs": []
>                         },
>-                        "name": "size"
>+                        "name": "size",
>+                        "escapedName": "size"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -115,48 +110,51 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "setDimensions",
>+                "escapedName": "setDimensions",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "width"
>+                        "name": "width",
>+                        "escapedName": "width"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "unsigned long"
>+                            "idlType": "unsigned long",
>+                            "extAttrs": []
>                         },
>-                        "name": "height"
>+                        "name": "height",
>+                        "escapedName": "height"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -165,4 +163,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json
>index 4d25f3d9317e12da6d73723cefa7ff8a071be053..133891d461db315c17b4184b0d7443dd35feaf50 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json
>@@ -11,18 +11,21 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "value",
>+                "escapedName": "value",
>                 "extAttrs": [
>                     {
>                         "name": "Replaceable",
>-                        "arguments": null
>+                        "arguments": null,
>+                        "type": "extended-attribute",
>+                        "rhs": null
>                     }
>                 ]
>             },
>@@ -30,20 +33,19 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "increment",
>+                "escapedName": "increment",
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -51,4 +53,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/sequence.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/sequence.json
>index 7ddd402b402aee67c8b0a697d5fc006306e541b6..ead0cdd862c7867cc8cb2e0b55bbca4367aeb89d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/sequence.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/sequence.json
>@@ -8,41 +8,42 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "drawPolygon",
>+                "escapedName": "drawPolygon",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": true,
>+                            "type": "argument-type",
>                             "generic": "sequence",
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>                             "idlType": {
>-                                "sequence": false,
>+                                "type": "argument-type",
>                                 "generic": null,
>                                 "nullable": false,
>-                                "array": false,
>                                 "union": false,
>-                                "idlType": "float"
>-                            }
>+                                "idlType": "float",
>+                                "extAttrs": []
>+                            },
>+                            "extAttrs": []
>                         },
>-                        "name": "coordinates"
>+                        "name": "coordinates",
>+                        "escapedName": "coordinates"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -51,27 +52,26 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": true,
>+                    "type": "return-type",
>                     "generic": "sequence",
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>                     "idlType": {
>-                        "sequence": false,
>+                        "type": "return-type",
>                         "generic": null,
>                         "nullable": false,
>-                        "array": false,
>                         "union": false,
>-                        "idlType": "float"
>-                    }
>+                        "idlType": "float",
>+                        "extAttrs": []
>+                    },
>+                    "extAttrs": []
>                 },
>                 "name": "getInflectionPoints",
>+                "escapedName": "getInflectionPoints",
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -81,33 +81,62 @@
>     },
>     {
>         "type": "interface",
>-        "name": "Foo",
>+        "name": "I",
>         "partial": false,
>         "members": [
>-
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "sequence"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>-                "name": "bar",
>-                "arguments": [],
>+                "name": "f1",
>+                "escapedName": "f1",
>+                "arguments": [
>+                    {
>+                        "optional": false,
>+                        "variadic": false,
>+                        "default": null,
>+                        "extAttrs": [],
>+                        "idlType": {
>+                            "type": "argument-type",
>+                            "generic": "sequence",
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": {
>+                                "type": "argument-type",
>+                                "generic": null,
>+                                "nullable": false,
>+                                "union": false,
>+                                "idlType": "long",
>+                                "extAttrs": [
>+                                    {
>+                                        "name": "XAttr",
>+                                        "arguments": null,
>+                                        "type": "extended-attribute",
>+                                        "rhs": null
>+                                    }
>+                                ]
>+                            },
>+                            "extAttrs": []
>+                        },
>+                        "name": "arg",
>+                        "escapedName": "arg"
>+                    }
>+                ],
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>-    }    
>-]
>\ No newline at end of file
>+    }
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/serializer.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/serializer.json
>deleted file mode 100644
>index 79b501fcbc4c7c492607b51d7f5f0ce41ce02bd8..0000000000000000000000000000000000000000
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/serializer.json
>+++ /dev/null
>@@ -1,591 +0,0 @@
>-[
>-    {
>-        "type": "interface",
>-        "name": "Transaction",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "Account"
>-                },
>-                "name": "from",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "Account"
>-                },
>-                "name": "to",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "float"
>-                },
>-                "name": "amount",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "description",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "name",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "operation": {
>-                    "name": "serialize",
>-                    "arguments": []
>-                },
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Transaction2",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "Account2"
>-                },
>-                "name": "from",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "Account2"
>-                },
>-                "name": "to",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "float"
>-                },
>-                "name": "amount",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "description",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": true,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternMap": true,
>-                "names": [
>-                    "from",
>-                    "to",
>-                    "amount",
>-                    "description"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account2",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "name",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "name": "number",
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account3",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "name",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternMap": true,
>-                "names": [
>-                    "attribute"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account4",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "operation",
>-                "getter": true,
>-                "setter": false,
>-                "creator": false,
>-                "deleter": false,
>-                "legacycaller": false,
>-                "static": false,
>-                "stringifier": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "object"
>-                },
>-                "name": "getItem",
>-                "arguments": [
>-                    {
>-                        "optional": false,
>-                        "variadic": false,
>-                        "extAttrs": [],
>-                        "idlType": {
>-                            "sequence": false,
>-                            "generic": null,
>-                            "nullable": false,
>-                            "array": false,
>-                            "union": false,
>-                            "idlType": "unsigned long"
>-                        },
>-                        "name": "index"
>-                    }
>-                ],
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternMap": true,
>-                "names": [
>-                    "getter"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account5",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "secondname",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternMap": true,
>-                "names": [
>-                    "inherit",
>-                    "secondname"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": "Account",
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account6",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "secondname",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternMap": true,
>-                "names": [
>-                    "inherit",
>-                    "attribute"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": "Account",
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account7",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "DOMString"
>-                },
>-                "name": "name",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "attribute",
>-                "static": false,
>-                "stringifier": false,
>-                "inherit": false,
>-                "readonly": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "unsigned long"
>-                },
>-                "name": "number",
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternList": true,
>-                "names": [
>-                    "name",
>-                    "number"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    },
>-    {
>-        "type": "interface",
>-        "name": "Account8",
>-        "partial": false,
>-        "members": [
>-            {
>-                "type": "operation",
>-                "getter": true,
>-                "setter": false,
>-                "creator": false,
>-                "deleter": false,
>-                "legacycaller": false,
>-                "static": false,
>-                "stringifier": false,
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "object"
>-                },
>-                "name": "getItem",
>-                "arguments": [
>-                    {
>-                        "optional": false,
>-                        "variadic": false,
>-                        "extAttrs": [],
>-                        "idlType": {
>-                            "sequence": false,
>-                            "generic": null,
>-                            "nullable": false,
>-                            "array": false,
>-                            "union": false,
>-                            "idlType": "unsigned long"
>-                        },
>-                        "name": "index"
>-                    }
>-                ],
>-                "extAttrs": []
>-            },
>-            {
>-                "type": "serializer",
>-                "patternList": true,
>-                "names": [
>-                    "getter"
>-                ],
>-                "extAttrs": []
>-            }
>-        ],
>-        "inheritance": null,
>-        "extAttrs": []
>-    }
>-]
>\ No newline at end of file
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/setlike.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/setlike.json
>index d44043a944aa9bd58223a96ca7b7deeef6055091..d8583538fd0f0a1f1e4b3e03942c2aca5f615270 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/setlike.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/setlike.json
>@@ -6,14 +6,16 @@
>         "members": [
>             {
>                 "type": "setlike",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "long"
>-                },
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": []
>+                    }
>+                ],
>                 "readonly": false,
>                 "extAttrs": []
>             }
>@@ -28,20 +30,52 @@
>         "members": [
>             {
>                 "type": "setlike",
>-                "idlType": {
>-                    "sequence": false,
>-                    "generic": null,
>-                    "nullable": false,
>-                    "array": false,
>-                    "union": false,
>-                    "idlType": "long"
>-                },
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": []
>+                    }
>+                ],
>                 "readonly": true,
>                 "extAttrs": []
>             }
>         ],
>         "inheritance": null,
>         "extAttrs": []
>+    },
>+    {
>+        "type": "interface",
>+        "name": "SetLikeExt",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "setlike",
>+                "idlType": [
>+                    {
>+                        "type": null,
>+                        "generic": null,
>+                        "nullable": false,
>+                        "union": false,
>+                        "idlType": "long",
>+                        "extAttrs": [
>+                            {
>+                                "name": "XAttr",
>+                                "arguments": null,
>+                                "type": "extended-attribute",
>+                                "rhs": null
>+                            }
>+                        ]
>+                    }
>+                ],
>+                "readonly": false,
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>     }
> ]
>-
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/static.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/static.json
>index faab12b2966cebe10cf7817cebc94e5f007a4065..d0ddf35ec6e4b5da6acdf203eae3daa5f0132d19 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/static.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/static.json
>@@ -19,14 +19,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "cx",
>+                "escapedName": "cx",
>                 "extAttrs": []
>             },
>             {
>@@ -36,14 +37,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "cy",
>+                "escapedName": "cy",
>                 "extAttrs": []
>             },
>             {
>@@ -53,14 +55,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "radius",
>+                "escapedName": "radius",
>                 "extAttrs": []
>             },
>             {
>@@ -70,76 +73,82 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "long"
>+                    "idlType": "long",
>+                    "extAttrs": []
>                 },
>                 "name": "triangulationCount",
>+                "escapedName": "triangulationCount",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": true,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Point"
>+                    "idlType": "Point",
>+                    "extAttrs": []
>                 },
>                 "name": "triangulate",
>+                "escapedName": "triangulate",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Circle"
>+                            "idlType": "Circle",
>+                            "extAttrs": []
>                         },
>-                        "name": "c1"
>+                        "name": "c1",
>+                        "escapedName": "c1"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Circle"
>+                            "idlType": "Circle",
>+                            "extAttrs": []
>                         },
>-                        "name": "c2"
>+                        "name": "c2",
>+                        "escapedName": "c2"
>                     },
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Circle"
>+                            "idlType": "Circle",
>+                            "extAttrs": []
>                         },
>-                        "name": "c3"
>+                        "name": "c3",
>+                        "escapedName": "c3"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -148,4 +157,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json
>index 196ee6f1a7c07f6d17c7132bced8b38149f1c8d6..dbca7f17902c2b317e9de74ca7a54b1e8c120783 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "id",
>+                "escapedName": "id",
>                 "extAttrs": []
>             },
>             {
>@@ -28,14 +29,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             }
>         ],
>@@ -43,8 +45,10 @@
>         "extAttrs": [
>             {
>                 "name": "Constructor",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-custom.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-custom.json
>index b4ab7392e5a69b871ab9545aa66a588d0c70e527..c13df6ef10c0c505008448c055e1911def33c9da 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-custom.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-custom.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "id",
>+                "escapedName": "id",
>                 "extAttrs": []
>             },
>             {
>@@ -28,14 +29,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": true,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "familyName",
>+                "escapedName": "familyName",
>                 "extAttrs": []
>             },
>             {
>@@ -45,34 +47,34 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "givenName",
>+                "escapedName": "givenName",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -81,8 +83,10 @@
>         "extAttrs": [
>             {
>                 "name": "Constructor",
>-                "arguments": null
>+                "arguments": null,
>+                "type": "extended-attribute",
>+                "rhs": null
>             }
>         ]
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier.json
>index ad3abde85f4bbc610d9d806d4bde52f0801ddc97..a4f23e03f66d4213bf55fcd43b406eb545879333 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier.json
>@@ -8,20 +8,19 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": null,
>+                "escapedName": null,
>                 "arguments": [],
>                 "extAttrs": []
>             }
>@@ -31,16 +30,14 @@
>     },
>     {
>         "type": "interface",
>-        "name": "A",
>+        "name": "B",
>         "partial": false,
>         "members": [
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": true,
>                 "extAttrs": []
>@@ -49,4 +46,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasnull.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasnull.json
>index 8bacb967acc1e1eff834532e0b266290117f6b27..d5156bcb4f1b5ddb4db5b2a2518f9cf0a7b41745 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasnull.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasnull.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             },
>             {
>@@ -28,42 +29,44 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "owner",
>+                "escapedName": "owner",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "isMemberOfBreed",
>+                "escapedName": "isMemberOfBreed",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [
>                             {
>                                 "name": "TreatNullAs",
>                                 "arguments": null,
>+                                "type": "extended-attribute",
>                                 "rhs": {
>                                     "type": "identifier",
>                                     "value": "EmptyString"
>@@ -71,14 +74,15 @@
>                             }
>                         ],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "breedName"
>+                        "name": "breedName",
>+                        "escapedName": "breedName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -87,4 +91,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasundefined.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasundefined.json
>index 91c4d25f5d1d2fb8f58acfe657531d3168679fba..1e98315d9f13bfb0298d8a74290ab90e69d961d4 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasundefined.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/treatasundefined.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "name",
>+                "escapedName": "name",
>                 "extAttrs": []
>             },
>             {
>@@ -28,42 +29,44 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "DOMString"
>+                    "idlType": "DOMString",
>+                    "extAttrs": []
>                 },
>                 "name": "owner",
>+                "escapedName": "owner",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "isMemberOfBreed",
>+                "escapedName": "isMemberOfBreed",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [
>                             {
>                                 "name": "TreatUndefinedAs",
>                                 "arguments": null,
>+                                "type": "extended-attribute",
>                                 "rhs": {
>                                     "type": "identifier",
>                                     "value": "EmptyString"
>@@ -71,14 +74,15 @@
>                             }
>                         ],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "DOMString"
>+                            "idlType": "DOMString",
>+                            "extAttrs": []
>                         },
>-                        "name": "breedName"
>+                        "name": "breedName",
>+                        "escapedName": "breedName"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -87,4 +91,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef-union.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef-union.json
>index 9c87672c8aebb1074943530d5de1edd546d3ae22..31e24198ab130f3cd7efdd3e80a4baaf6bb213e3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef-union.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef-union.json
>@@ -1,49 +1,48 @@
> [
>-   {
>-      "type" : "typedef",
>-      "idlType" : {
>-         "nullable" : false,
>-         "generic" : null,
>-         "union" : true,
>-         "idlType" : [
>-            {
>-               "union" : false,
>-               "generic" : null,
>-               "nullable" : false,
>-               "array" : false,
>-               "sequence" : false,
>-               "idlType" : "ImageData"
>-            },
>-            {
>-               "generic" : null,
>-               "union" : false,
>-               "nullable" : false,
>-               "array" : false,
>-               "idlType" : "HTMLImageElement",
>-               "sequence" : false
>-            },
>-            {
>-               "array" : false,
>-               "sequence" : false,
>-               "idlType" : "HTMLCanvasElement",
>-               "generic" : null,
>-               "union" : false,
>-               "nullable" : false
>-            },
>-            {
>-               "union" : false,
>-               "generic" : null,
>-               "nullable" : false,
>-               "array" : false,
>-               "sequence" : false,
>-               "idlType" : "HTMLVideoElement"
>-            }
>-         ],
>-         "sequence" : false,
>-         "array" : false
>-      },
>-      "name" : "TexImageSource",
>-      "extAttrs" : [],
>-      "typeExtAttrs" : []
>-   }
>+    {
>+        "type": "typedef",
>+        "idlType": {
>+            "type": "typedef-type",
>+            "generic": null,
>+            "nullable": false,
>+            "union": true,
>+            "idlType": [
>+                {
>+                    "type": null,
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "ImageData",
>+                    "extAttrs": []
>+                },
>+                {
>+                    "type": null,
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "HTMLImageElement",
>+                    "extAttrs": []
>+                },
>+                {
>+                    "type": null,
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "HTMLCanvasElement",
>+                    "extAttrs": []
>+                },
>+                {
>+                    "type": null,
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": false,
>+                    "idlType": "HTMLVideoElement",
>+                    "extAttrs": []
>+                }
>+            ],
>+            "extAttrs": []
>+        },
>+        "name": "TexImageSource",
>+        "extAttrs": []
>+    }
> ]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef.json
>index d0854fa3d2626855da2eed1419e32dba7f3d9cfc..35f988e721e75e9808a6a00a749aef3fb051b0e3 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typedef.json
>@@ -11,14 +11,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "x",
>+                "escapedName": "x",
>                 "extAttrs": []
>             },
>             {
>@@ -28,14 +29,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "float"
>+                    "idlType": "float",
>+                    "extAttrs": []
>                 },
>                 "name": "y",
>+                "escapedName": "y",
>                 "extAttrs": []
>             }
>         ],
>@@ -45,19 +47,19 @@
>     {
>         "type": "typedef",
>         "idlType": {
>-            "sequence": true,
>+            "type": "typedef-type",
>             "generic": "sequence",
>             "nullable": false,
>-            "array": false,
>             "union": false,
>             "idlType": {
>-                "sequence": false,
>+                "type": "typedef-type",
>                 "generic": null,
>                 "nullable": false,
>-                "array": false,
>                 "union": false,
>-                "idlType": "Point"
>-            }
>+                "idlType": "Point",
>+                "extAttrs": []
>+            },
>+            "extAttrs": []
>         },
>         "name": "PointSequence",
>         "extAttrs": []
>@@ -74,14 +76,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Point"
>+                    "idlType": "Point",
>+                    "extAttrs": []
>                 },
>                 "name": "topleft",
>+                "escapedName": "topleft",
>                 "extAttrs": []
>             },
>             {
>@@ -91,14 +94,15 @@
>                 "inherit": false,
>                 "readonly": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Point"
>+                    "idlType": "Point",
>+                    "extAttrs": []
>                 },
>                 "name": "bottomright",
>+                "escapedName": "bottomright",
>                 "extAttrs": []
>             }
>         ],
>@@ -117,48 +121,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "Rect"
>+                    "idlType": "Rect",
>+                    "extAttrs": []
>                 },
>                 "name": "bounds",
>+                "escapedName": "bounds",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "pointWithinBounds",
>+                "escapedName": "pointWithinBounds",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "Point"
>+                            "idlType": "Point",
>+                            "extAttrs": []
>                         },
>-                        "name": "p"
>+                        "name": "p",
>+                        "escapedName": "p"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -167,34 +173,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "boolean"
>+                    "idlType": "boolean",
>+                    "extAttrs": []
>                 },
>                 "name": "allPointsWithinBounds",
>+                "escapedName": "allPointsWithinBounds",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "PointSequence"
>+                            "idlType": "PointSequence",
>+                            "extAttrs": []
>                         },
>-                        "name": "ps"
>+                        "name": "ps",
>+                        "escapedName": "ps"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -206,16 +213,17 @@
>     {
>         "type": "typedef",
>         "idlType": {
>-            "sequence": false,
>+            "type": "typedef-type",
>             "generic": null,
>             "nullable": false,
>-            "array": false,
>             "union": false,
>             "idlType": "octet",
>             "extAttrs": [
>                 {
>                     "name": "Clamp",
>-                    "arguments": null
>+                    "arguments": null,
>+                    "type": "extended-attribute",
>+                    "rhs": null
>                 }
>             ]
>         },
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typesuffixes.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typesuffixes.json
>index 790c444ef461b05a8ff766228d9c1ced38635b39..52870c22f4b47616e2df15d62752f950d03e0b07 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typesuffixes.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/typesuffixes.json
>@@ -8,42 +8,42 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "test",
>+                "escapedName": "test",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": false,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": true,
>+                            "type": "argument-type",
>                             "generic": "sequence",
>                             "nullable": true,
>-                            "array": false,
>                             "union": false,
>                             "idlType": {
>-                                "sequence": false,
>+                                "type": "argument-type",
>                                 "generic": null,
>                                 "nullable": true,
>-                                "array": 1,
>-                                "nullableArray": [false],
>                                 "union": false,
>-                                "idlType": "DOMString"
>-                            }
>+                                "idlType": "DOMString",
>+                                "extAttrs": []
>+                            },
>+                            "extAttrs": []
>                         },
>-                        "name": "foo"
>+                        "name": "foo",
>+                        "escapedName": "foo"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -52,4 +52,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/uniontype.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/uniontype.json
>index 9da5e79f3625ef6c2b11ed204aef90742d925c61..90eb074ef3a0a719e9ecd5f67b47cd52b682f094 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/uniontype.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/uniontype.json
>@@ -1,127 +1,130 @@
> [
>-   {
>-      "partial": false,
>-      "members": [
>-         {
>-            "idlType": {
>-               "idlType": [
>-                  {
>-                     "array": false,
>-                     "union": false,
>-                     "sequence": false,
>-                     "generic": null,
>-                     "idlType": "float",
>-                     "nullable": false
>-                  },
>-                  {
>-                     "idlType": [
>+    {
>+        "type": "interface",
>+        "name": "Union",
>+        "partial": false,
>+        "members": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": true,
>+                    "idlType": [
>                         {
>-                           "nullable": false,
>-                           "idlType": "Date",
>-                           "sequence": false,
>-                           "generic": null,
>-                           "union": false,
>-                           "array": false
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "float",
>+                            "extAttrs": []
>                         },
>                         {
>-                           "nullable": false,
>-                           "idlType": "Event",
>-                           "generic": null,
>-                           "sequence": false,
>-                           "array": false,
>-                           "union": false
>-                        }
>-                     ],
>-                     "nullable": false,
>-                     "sequence": false,
>-                     "generic": null,
>-                     "array": false,
>-                     "union": true
>-                  },
>-                  {
>-                     "generic": null,
>-                     "sequence": false,
>-                     "idlType": [
>-                        {
>-                           "array": false,
>-                           "union": false,
>-                           "sequence": false,
>-                           "generic": null,
>-                           "nullable": false,
>-                           "idlType": "Node"
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": true,
>+                            "idlType": [
>+                                {
>+                                    "type": null,
>+                                    "generic": null,
>+                                    "nullable": false,
>+                                    "union": false,
>+                                    "idlType": "Date",
>+                                    "extAttrs": []
>+                                },
>+                                {
>+                                    "type": null,
>+                                    "generic": null,
>+                                    "nullable": false,
>+                                    "union": false,
>+                                    "idlType": "Event",
>+                                    "extAttrs": []
>+                                }
>+                            ],
>+                            "extAttrs": []
>                         },
>                         {
>-                           "nullable": false,
>-                           "idlType": "DOMString",
>-                           "sequence": false,
>-                           "generic": null,
>-                           "array": false,
>-                           "union": false
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": true,
>+                            "union": true,
>+                            "idlType": [
>+                                {
>+                                    "type": null,
>+                                    "generic": null,
>+                                    "nullable": false,
>+                                    "union": false,
>+                                    "idlType": "Node",
>+                                    "extAttrs": []
>+                                },
>+                                {
>+                                    "type": null,
>+                                    "generic": null,
>+                                    "nullable": false,
>+                                    "union": false,
>+                                    "idlType": "DOMString",
>+                                    "extAttrs": []
>+                                }
>+                            ],
>+                            "extAttrs": []
>                         }
>-                     ],
>-                     "nullable": true,
>-                     "union": true,
>-                     "array": false
>-                  }
>-               ],
>-               "nullable": false,
>-               "generic": null,
>-               "sequence": false,
>-               "union": true,
>-               "array": false
>+                    ],
>+                    "extAttrs": []
>+                },
>+                "name": "test",
>+                "escapedName": "test",
>+                "extAttrs": []
>             },
>-            "name": "test",
>-            "inherit": false,
>-            "type": "attribute",
>-            "extAttrs": [],
>-            "readonly": false,
>-            "stringifier": false,
>-            "static": false
>-         },
>-         {
>-            "readonly": false,
>-            "extAttrs": [],
>-            "stringifier": false,
>-            "static": false,
>-            "name": "test2",
>-            "idlType": {
>-               "nullable": false,
>-               "idlType": [
>-                  {
>-                     "extAttrs": [
>+            {
>+                "type": "attribute",
>+                "static": false,
>+                "stringifier": false,
>+                "inherit": false,
>+                "readonly": false,
>+                "idlType": {
>+                    "type": "attribute-type",
>+                    "generic": null,
>+                    "nullable": false,
>+                    "union": true,
>+                    "idlType": [
>                         {
>-                           "name": "EnforceRange",
>-                           "arguments": null
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "long",
>+                            "extAttrs": [
>+                                {
>+                                    "name": "EnforceRange",
>+                                    "arguments": null,
>+                                    "type": "extended-attribute",
>+                                    "rhs": null
>+                                }
>+                            ]
>+                        },
>+                        {
>+                            "type": null,
>+                            "generic": null,
>+                            "nullable": false,
>+                            "union": false,
>+                            "idlType": "Date",
>+                            "extAttrs": []
>                         }
>-                     ],
>-                     "nullable": false,
>-                     "idlType": "long",
>-                     "generic": null,
>-                     "sequence": false,
>-                     "array": false,
>-                     "union": false
>-                  },
>-                  {
>-                     "array": false,
>-                     "union": false,
>-                     "sequence": false,
>-                     "generic": null,
>-                     "idlType": "Date",
>-                     "nullable": false
>-                  }
>-               ],
>-               "generic": null,
>-               "sequence": false,
>-               "union": true,
>-               "array": false
>-            },
>-            "inherit": false,
>-            "type": "attribute"
>-         }
>-      ],
>-      "inheritance": null,
>-      "name": "Union",
>-      "extAttrs": [],
>-      "type": "interface"
>-   }
>+                    ],
>+                    "extAttrs": []
>+                },
>+                "name": "test2",
>+                "escapedName": "test2",
>+                "extAttrs": []
>+            }
>+        ],
>+        "inheritance": null,
>+        "extAttrs": []
>+    }
> ]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/variadic-operations.json b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/variadic-operations.json
>index 431ec0cb1150e0084cd8c9ac0e5f671d024a2808..3280b7b6a78a9419e008efee46c0f7e5dc2b5bac 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/variadic-operations.json
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/variadic-operations.json
>@@ -11,48 +11,50 @@
>                 "inherit": false,
>                 "readonly": true,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "attribute-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "unsigned long"
>+                    "idlType": "unsigned long",
>+                    "extAttrs": []
>                 },
>                 "name": "cardinality",
>+                "escapedName": "cardinality",
>                 "extAttrs": []
>             },
>             {
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "union",
>+                "escapedName": "union",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": true,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "long"
>+                            "idlType": "long",
>+                            "extAttrs": []
>                         },
>-                        "name": "ints"
>+                        "name": "ints",
>+                        "escapedName": "ints"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -61,34 +63,35 @@
>                 "type": "operation",
>                 "getter": false,
>                 "setter": false,
>-                "creator": false,
>                 "deleter": false,
>-                "legacycaller": false,
>                 "static": false,
>                 "stringifier": false,
>                 "idlType": {
>-                    "sequence": false,
>+                    "type": "return-type",
>                     "generic": null,
>                     "nullable": false,
>-                    "array": false,
>                     "union": false,
>-                    "idlType": "void"
>+                    "idlType": "void",
>+                    "extAttrs": []
>                 },
>                 "name": "intersection",
>+                "escapedName": "intersection",
>                 "arguments": [
>                     {
>                         "optional": false,
>                         "variadic": true,
>+                        "default": null,
>                         "extAttrs": [],
>                         "idlType": {
>-                            "sequence": false,
>+                            "type": "argument-type",
>                             "generic": null,
>                             "nullable": false,
>-                            "array": false,
>                             "union": false,
>-                            "idlType": "long"
>+                            "idlType": "long",
>+                            "extAttrs": []
>                         },
>-                        "name": "ints"
>+                        "name": "ints",
>+                        "escapedName": "ints"
>                     }
>                 ],
>                 "extAttrs": []
>@@ -97,4 +100,4 @@
>         "inheritance": null,
>         "extAttrs": []
>     }
>-]
>\ No newline at end of file
>+]
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/w3c-import.log
>index d79ee75337bedf279e72aedbf07cd15a1e740993..0e29fe78388e6038725f1d1802f6b5670685e058 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -15,10 +15,8 @@ None
> ------------------------------------------------------------------------
> List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/allowany.json
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/array.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/attributes.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/callback.json
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/caller.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constants.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/constructor.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/dictionary-inherits.json
>@@ -28,7 +26,6 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/enum.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/equivalent-decl.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception-inheritance.json
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/exception.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/extended-attributes.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/generic.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/getter-setter.json
>@@ -41,6 +38,7 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/iterator.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/legacyiterable.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/maplike.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/mixin.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namedconstructor.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/namespace.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/nointerfaceobject.json
>@@ -51,13 +49,13 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/overridebuiltins.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/partial-interface.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/primitives.json
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/promise-void.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/prototyperoot.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/putforwards.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/record.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/reg-operations.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/replaceable.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/sequence.json
>-/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/serializer.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/setlike.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/static.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax/json/stringifier-attribute.json
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/acquire.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/acquire.js
>new file mode 100644
>index 0000000000000000000000000000000000000000..6f37dd6083c3c75dfe561727e9a843465e3cfa6c
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/acquire.js
>@@ -0,0 +1,8 @@
>+"use strict";
>+
>+const { collect } = require("./collect");
>+const fs = require("fs");
>+
>+for (const test of collect("syntax")) {
>+  fs.writeFileSync(test.jsonPath, `${JSON.stringify(test.ast, null, 4)}\n`)
>+}
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/collect.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/collect.js
>new file mode 100644
>index 0000000000000000000000000000000000000000..7e3d9d3bf31267578c0ce2046eec3f5245c573dc
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/collect.js
>@@ -0,0 +1,59 @@
>+"use strict";
>+
>+const wp = require("../../lib/webidl2");
>+const pth = require("path");
>+const fs = require("fs");
>+const jdp = require("jsondiffpatch");
>+
>+/**
>+ * Collects test items from the specified directory
>+ * @param {string} base
>+ */
>+function* collect(base, { expectError } = {}) {
>+  base = pth.join(__dirname, "..", base);
>+  const dir = pth.join(base, "idl");
>+  const idls = fs.readdirSync(dir)
>+    .filter(it => (/\.widl$/).test(it))
>+    .map(it => pth.join(dir, it));
>+
>+  for (const path of idls) {
>+    const optFile = pth.join(base, "opt", pth.basename(path)).replace(".widl", ".json");
>+    let opt;
>+    if (fs.existsSync(optFile))
>+      opt = JSON.parse(fs.readFileSync(optFile, "utf8"));
>+
>+    try {
>+      const ast = wp.parse(fs.readFileSync(path, "utf8").replace(/\r\n/g, "\n"), opt);
>+      yield new TestItem({ ast, path, opt });
>+    }
>+    catch (error) {
>+      if (expectError) {
>+        yield new TestItem({ path, error });
>+      }
>+      else {
>+        throw error;
>+      }
>+    }
>+  }
>+};
>+
>+
>+class TestItem {
>+  constructor({ ast, path, error, opt }) {
>+    this.ast = ast;
>+    this.path = path;
>+    this.error = error;
>+    this.opt = opt;
>+    this.jsonPath = pth.join(pth.dirname(path), "../json", pth.basename(path).replace(".widl", ".json"));
>+  }
>+
>+  readJSON() {
>+    return JSON.parse(fs.readFileSync(this.jsonPath, "utf8"));
>+  }
>+
>+  diff(target = this.readJSON()) {
>+    return jdp.diff(target, this.ast);
>+  }
>+}
>+
>+module.exports.collect = collect;
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/w3c-import.log
>new file mode 100644
>index 0000000000000000000000000000000000000000..8a5bd4d07a7af0bf31d2e9630d6916794a2d70ac
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/w3c-import.log
>@@ -0,0 +1,18 @@
>+The tests in this directory were imported from the W3C repository.
>+Do NOT modify these tests directly in WebKit.
>+Instead, create a pull request on the WPT github:
>+	https://github.com/web-platform-tests/wpt
>+
>+Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
>+
>+Do NOT modify or remove this file.
>+
>+------------------------------------------------------------------------
>+Properties requiring vendor prefixes:
>+None
>+Property values requiring vendor prefixes:
>+None
>+------------------------------------------------------------------------
>+List of files:
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/acquire.js
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/util/collect.js
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/w3c-import.log
>index b026795ae9999c59b96c5dda9e2c92edb6a19377..47b7cb9fe563070381711768f19836003c2942f5 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -17,3 +17,4 @@ List of files:
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/invalid.js
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/mocha.opts
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/syntax.js
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/writer.js
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/web/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/web/w3c-import.log
>index b4cf99e1a5a3642f21f9b29d3bf6660dd130a3f7..44bdb9fb5454d1d0401779eed26349ed305fbd6e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/web/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/web/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/writer.js b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/writer.js
>new file mode 100644
>index 0000000000000000000000000000000000000000..e84076b4f28ce38cbb41e47681ac97843df0e427
>--- /dev/null
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/test/writer.js
>@@ -0,0 +1,23 @@
>+"use strict";
>+
>+const { collect } = require("./util/collect");
>+const wp = require("../lib/webidl2");
>+const writer = require("../lib/writer");
>+const expect = require("expect");
>+const debug = true;
>+
>+describe("Rewrite and parses all of the IDLs to produce the same ASTs", () => {
>+  for (const test of collect("syntax")) {
>+    it(`should produce the same AST for ${test.path}`, () => {
>+      try {
>+        const diff = test.diff(wp.parse(writer.write(test.ast), test.opt));
>+        if (diff && debug) console.log(JSON.stringify(diff, null, 4));
>+        expect(diff).toBe(undefined);
>+      }
>+      catch (e) {
>+        console.log(e.toString());
>+        throw e;
>+      }
>+    });
>+  }
>+});
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/w3c-import.log b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/w3c-import.log
>index 7aea1e13eb5ce5a04f457bb09716c009ba7e7ff2..82459ec25789f11afac3b4eb4264967d50198737 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/w3c-import.log
>+++ b/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/w3c-import.log
>@@ -1,7 +1,7 @@
> The tests in this directory were imported from the W3C repository.
> Do NOT modify these tests directly in WebKit.
> Instead, create a pull request on the WPT github:
>-	https://github.com/w3c/web-platform-tests
>+	https://github.com/web-platform-tests/wpt
> 
> Then run the Tools/Scripts/import-w3c-tests in WebKit to reimport
> 
>@@ -14,8 +14,10 @@ Property values requiring vendor prefixes:
> None
> ------------------------------------------------------------------------
> List of files:
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/CHANGELOG.md
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/LICENSE
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/README.md
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/coverage.html
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/index.js
>+/LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package-lock.json
> /LayoutTests/imported/w3c/web-platform-tests/resources/webidl2/package.json
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any-expected.txt
>index 7c0a1b6e153256df6c0d8cd2eeeac1389ef63b4a..0da111f8a603128f5bf49c7d25e6dc48f6ce8f51 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any-expected.txt
>@@ -8,32 +8,19 @@ PASS URL interface: existence and properties of interface prototype object
> PASS URL interface: existence and properties of interface prototype object's "constructor" property 
> PASS URL interface: existence and properties of interface prototype object's @@unscopables property 
> PASS URL interface: attribute href 
>-PASS Unscopable handled correctly for href property on URL 
> PASS URL interface: stringifier 
> PASS URL interface: attribute origin 
>-PASS Unscopable handled correctly for origin property on URL 
> PASS URL interface: attribute protocol 
>-PASS Unscopable handled correctly for protocol property on URL 
> PASS URL interface: attribute username 
>-PASS Unscopable handled correctly for username property on URL 
> PASS URL interface: attribute password 
>-PASS Unscopable handled correctly for password property on URL 
> PASS URL interface: attribute host 
>-PASS Unscopable handled correctly for host property on URL 
> PASS URL interface: attribute hostname 
>-PASS Unscopable handled correctly for hostname property on URL 
> PASS URL interface: attribute port 
>-PASS Unscopable handled correctly for port property on URL 
> PASS URL interface: attribute pathname 
>-PASS Unscopable handled correctly for pathname property on URL 
> PASS URL interface: attribute search 
>-PASS Unscopable handled correctly for search property on URL 
> PASS URL interface: attribute searchParams 
>-PASS Unscopable handled correctly for searchParams property on URL 
> PASS URL interface: attribute hash 
>-PASS Unscopable handled correctly for hash property on URL 
> PASS URL interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on URL 
> PASS URL must be primary interface of new URL("http://foo") 
> PASS Stringification of new URL("http://foo") 
> PASS URL interface: new URL("http://foo") must inherit property "href" with the proper type 
>@@ -57,30 +44,19 @@ PASS URLSearchParams interface: existence and properties of interface prototype
> PASS URLSearchParams interface: existence and properties of interface prototype object's "constructor" property 
> PASS URLSearchParams interface: existence and properties of interface prototype object's @@unscopables property 
> PASS URLSearchParams interface: operation append(USVString, USVString) 
>-PASS Unscopable handled correctly for append(USVString, USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation delete(USVString) 
>-PASS Unscopable handled correctly for delete(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation get(USVString) 
>-PASS Unscopable handled correctly for get(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation getAll(USVString) 
>-PASS Unscopable handled correctly for getAll(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation has(USVString) 
>-PASS Unscopable handled correctly for has(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation set(USVString, USVString) 
>-PASS Unscopable handled correctly for set(USVString, USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation sort() 
>-PASS Unscopable handled correctly for sort() on URLSearchParams 
> PASS Testing Symbol.iterator property of iterable interface URLSearchParams 
> PASS Testing pair iterable interface URLSearchParams 
> PASS URLSearchParams interface: stringifier 
> PASS URLSearchParams interface: operation entries() 
>-PASS Unscopable handled correctly for entries() on URLSearchParams 
> PASS URLSearchParams interface: operation keys() 
>-PASS Unscopable handled correctly for keys() on URLSearchParams 
> PASS URLSearchParams interface: operation values() 
>-PASS Unscopable handled correctly for values() on URLSearchParams 
> PASS URLSearchParams interface: operation forEach(function, any) 
>-PASS Unscopable handled correctly for forEach(function, any) on URLSearchParams 
> PASS URLSearchParams must be primary interface of new URLSearchParams("hi=there&thank=you") 
> PASS Stringification of new URLSearchParams("hi=there&thank=you") 
> PASS URLSearchParams interface: new URLSearchParams("hi=there&thank=you") must inherit property "append(USVString, USVString)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any.worker-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any.worker-expected.txt
>index 7c0a1b6e153256df6c0d8cd2eeeac1389ef63b4a..0da111f8a603128f5bf49c7d25e6dc48f6ce8f51 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any.worker-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/url/interfaces.any.worker-expected.txt
>@@ -8,32 +8,19 @@ PASS URL interface: existence and properties of interface prototype object
> PASS URL interface: existence and properties of interface prototype object's "constructor" property 
> PASS URL interface: existence and properties of interface prototype object's @@unscopables property 
> PASS URL interface: attribute href 
>-PASS Unscopable handled correctly for href property on URL 
> PASS URL interface: stringifier 
> PASS URL interface: attribute origin 
>-PASS Unscopable handled correctly for origin property on URL 
> PASS URL interface: attribute protocol 
>-PASS Unscopable handled correctly for protocol property on URL 
> PASS URL interface: attribute username 
>-PASS Unscopable handled correctly for username property on URL 
> PASS URL interface: attribute password 
>-PASS Unscopable handled correctly for password property on URL 
> PASS URL interface: attribute host 
>-PASS Unscopable handled correctly for host property on URL 
> PASS URL interface: attribute hostname 
>-PASS Unscopable handled correctly for hostname property on URL 
> PASS URL interface: attribute port 
>-PASS Unscopable handled correctly for port property on URL 
> PASS URL interface: attribute pathname 
>-PASS Unscopable handled correctly for pathname property on URL 
> PASS URL interface: attribute search 
>-PASS Unscopable handled correctly for search property on URL 
> PASS URL interface: attribute searchParams 
>-PASS Unscopable handled correctly for searchParams property on URL 
> PASS URL interface: attribute hash 
>-PASS Unscopable handled correctly for hash property on URL 
> PASS URL interface: operation toJSON() 
>-PASS Unscopable handled correctly for toJSON() on URL 
> PASS URL must be primary interface of new URL("http://foo") 
> PASS Stringification of new URL("http://foo") 
> PASS URL interface: new URL("http://foo") must inherit property "href" with the proper type 
>@@ -57,30 +44,19 @@ PASS URLSearchParams interface: existence and properties of interface prototype
> PASS URLSearchParams interface: existence and properties of interface prototype object's "constructor" property 
> PASS URLSearchParams interface: existence and properties of interface prototype object's @@unscopables property 
> PASS URLSearchParams interface: operation append(USVString, USVString) 
>-PASS Unscopable handled correctly for append(USVString, USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation delete(USVString) 
>-PASS Unscopable handled correctly for delete(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation get(USVString) 
>-PASS Unscopable handled correctly for get(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation getAll(USVString) 
>-PASS Unscopable handled correctly for getAll(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation has(USVString) 
>-PASS Unscopable handled correctly for has(USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation set(USVString, USVString) 
>-PASS Unscopable handled correctly for set(USVString, USVString) on URLSearchParams 
> PASS URLSearchParams interface: operation sort() 
>-PASS Unscopable handled correctly for sort() on URLSearchParams 
> PASS Testing Symbol.iterator property of iterable interface URLSearchParams 
> PASS Testing pair iterable interface URLSearchParams 
> PASS URLSearchParams interface: stringifier 
> PASS URLSearchParams interface: operation entries() 
>-PASS Unscopable handled correctly for entries() on URLSearchParams 
> PASS URLSearchParams interface: operation keys() 
>-PASS Unscopable handled correctly for keys() on URLSearchParams 
> PASS URLSearchParams interface: operation values() 
>-PASS Unscopable handled correctly for values() on URLSearchParams 
> PASS URLSearchParams interface: operation forEach(function, any) 
>-PASS Unscopable handled correctly for forEach(function, any) on URLSearchParams 
> PASS URLSearchParams must be primary interface of new URLSearchParams("hi=there&thank=you") 
> PASS Stringification of new URLSearchParams("hi=there&thank=you") 
> PASS URLSearchParams interface: new URLSearchParams("hi=there&thank=you") must inherit property "append(USVString, USVString)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/user-timing/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/user-timing/idlharness-expected.txt
>index ce0390b8fb0447acd3b9f3b844681a61d74bd56f..d83405d07f3ef8feafc0c67231330f8b7f976e71 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/user-timing/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/user-timing/idlharness-expected.txt
>@@ -1,14 +1,11 @@
> User Timing IDL tests
> 
> 
>+PASS Partial interface Performance: original interface defined 
> PASS Performance interface: operation mark(DOMString) 
>-PASS Unscopable handled correctly for mark(DOMString) on Performance 
> PASS Performance interface: operation clearMarks(DOMString) 
>-PASS Unscopable handled correctly for clearMarks(DOMString) on Performance 
> PASS Performance interface: operation measure(DOMString, DOMString, DOMString) 
>-PASS Unscopable handled correctly for measure(DOMString, DOMString, DOMString) on Performance 
> PASS Performance interface: operation clearMeasures(DOMString) 
>-PASS Unscopable handled correctly for clearMeasures(DOMString) on Performance 
> PASS Performance interface: window.performance must inherit property "mark(DOMString)" with the proper type 
> PASS Performance interface: calling mark(DOMString) on window.performance with too few arguments must throw TypeError 
> PASS Performance interface: window.performance must inherit property "clearMarks(DOMString)" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/Animation/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/Animation/idlharness-expected.txt
>index 07acd6f56df15baec15850b5c6c1b9ee90f1635c..12c06fdaeb6d248b53efe74f00ed25da5748ad87 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/Animation/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/Animation/idlharness-expected.txt
>@@ -6,39 +6,22 @@ PASS Animation interface: existence and properties of interface prototype object
> PASS Animation interface: existence and properties of interface prototype object's "constructor" property 
> PASS Animation interface: existence and properties of interface prototype object's @@unscopables property 
> PASS Animation interface: attribute id 
>-PASS Unscopable handled correctly for id property on Animation 
> PASS Animation interface: attribute effect 
>-PASS Unscopable handled correctly for effect property on Animation 
> PASS Animation interface: attribute timeline 
>-PASS Unscopable handled correctly for timeline property on Animation 
> PASS Animation interface: attribute startTime 
>-PASS Unscopable handled correctly for startTime property on Animation 
> PASS Animation interface: attribute currentTime 
>-PASS Unscopable handled correctly for currentTime property on Animation 
> PASS Animation interface: attribute playbackRate 
>-PASS Unscopable handled correctly for playbackRate property on Animation 
> PASS Animation interface: attribute playState 
>-PASS Unscopable handled correctly for playState property on Animation 
> PASS Animation interface: attribute pending 
>-PASS Unscopable handled correctly for pending property on Animation 
> PASS Animation interface: attribute ready 
>-PASS Unscopable handled correctly for ready property on Animation 
> PASS Animation interface: attribute finished 
>-PASS Unscopable handled correctly for finished property on Animation 
> PASS Animation interface: attribute onfinish 
>-PASS Unscopable handled correctly for onfinish property on Animation 
> PASS Animation interface: attribute oncancel 
>-PASS Unscopable handled correctly for oncancel property on Animation 
> PASS Animation interface: operation cancel() 
>-PASS Unscopable handled correctly for cancel() on Animation 
> PASS Animation interface: operation finish() 
>-PASS Unscopable handled correctly for finish() on Animation 
> PASS Animation interface: operation play() 
>-PASS Unscopable handled correctly for play() on Animation 
> PASS Animation interface: operation pause() 
>-PASS Unscopable handled correctly for pause() on Animation 
> PASS Animation interface: operation reverse() 
>-PASS Unscopable handled correctly for reverse() on Animation 
> PASS Animation must be primary interface of new Animation() 
> PASS Stringification of new Animation() 
> PASS Animation interface: new Animation() must inherit property "id" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationEffectTiming/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationEffectTiming/idlharness-expected.txt
>index 4b00d24ec6e5f006e1bdda616e761e77795137c8..e473c8f7933980998cbb3a3bf9c062a420f0d75a 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationEffectTiming/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationEffectTiming/idlharness-expected.txt
>@@ -6,21 +6,13 @@ PASS AnimationEffectTimingReadOnly interface: existence and properties of interf
> PASS AnimationEffectTimingReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS AnimationEffectTimingReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS AnimationEffectTimingReadOnly interface: attribute delay 
>-PASS Unscopable handled correctly for delay property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute endDelay 
>-PASS Unscopable handled correctly for endDelay property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute fill 
>-PASS Unscopable handled correctly for fill property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute iterationStart 
>-PASS Unscopable handled correctly for iterationStart property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute iterations 
>-PASS Unscopable handled correctly for iterations property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute duration 
>-PASS Unscopable handled correctly for duration property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute direction 
>-PASS Unscopable handled correctly for direction property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly interface: attribute easing 
>-PASS Unscopable handled correctly for easing property on AnimationEffectTimingReadOnly 
> PASS AnimationEffectTimingReadOnly must be primary interface of (new KeyframeEffectReadOnly(null, null)).timing 
> PASS Stringification of (new KeyframeEffectReadOnly(null, null)).timing 
> PASS AnimationEffectTimingReadOnly interface: (new KeyframeEffectReadOnly(null, null)).timing must inherit property "delay" with the proper type 
>@@ -38,21 +30,13 @@ PASS AnimationEffectTiming interface: existence and properties of interface prot
> PASS AnimationEffectTiming interface: existence and properties of interface prototype object's "constructor" property 
> PASS AnimationEffectTiming interface: existence and properties of interface prototype object's @@unscopables property 
> PASS AnimationEffectTiming interface: attribute delay 
>-PASS Unscopable handled correctly for delay property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute endDelay 
>-PASS Unscopable handled correctly for endDelay property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute fill 
>-PASS Unscopable handled correctly for fill property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute iterationStart 
>-PASS Unscopable handled correctly for iterationStart property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute iterations 
>-PASS Unscopable handled correctly for iterations property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute duration 
>-PASS Unscopable handled correctly for duration property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute direction 
>-PASS Unscopable handled correctly for direction property on AnimationEffectTiming 
> PASS AnimationEffectTiming interface: attribute easing 
>-PASS Unscopable handled correctly for easing property on AnimationEffectTiming 
> PASS AnimationEffectTiming must be primary interface of (new KeyframeEffect(null, null)).timing 
> PASS Stringification of (new KeyframeEffect(null, null)).timing 
> PASS AnimationEffectTiming interface: (new KeyframeEffect(null, null)).timing must inherit property "delay" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationPlaybackEvent/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationPlaybackEvent/idlharness-expected.txt
>index 5ff1407104011e7c094d6f64919c9e2409e6e014..14a0406f3f1acfc1d58cde1b684c2a4e4f88d0c6 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationPlaybackEvent/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/AnimationPlaybackEvent/idlharness-expected.txt
>@@ -6,9 +6,7 @@ PASS AnimationPlaybackEvent interface: existence and properties of interface pro
> PASS AnimationPlaybackEvent interface: existence and properties of interface prototype object's "constructor" property 
> PASS AnimationPlaybackEvent interface: existence and properties of interface prototype object's @@unscopables property 
> PASS AnimationPlaybackEvent interface: attribute currentTime 
>-PASS Unscopable handled correctly for currentTime property on AnimationPlaybackEvent 
> PASS AnimationPlaybackEvent interface: attribute timelineTime 
>-PASS Unscopable handled correctly for timelineTime property on AnimationPlaybackEvent 
> PASS AnimationPlaybackEvent must be primary interface of new AnimationPlaybackEvent('cancel') 
> PASS Stringification of new AnimationPlaybackEvent('cancel') 
> PASS AnimationPlaybackEvent interface: new AnimationPlaybackEvent('cancel') must inherit property "currentTime" with the proper type 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/DocumentTimeline/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/DocumentTimeline/idlharness-expected.txt
>index 878fcef3605f1fac71dd5153432ec75045419f7a..63eacc202bfd63eb5cee4e216e0a8c5d40e8f40d 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/DocumentTimeline/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/DocumentTimeline/idlharness-expected.txt
>@@ -6,7 +6,6 @@ PASS AnimationTimeline interface: existence and properties of interface prototyp
> PASS AnimationTimeline interface: existence and properties of interface prototype object's "constructor" property 
> PASS AnimationTimeline interface: existence and properties of interface prototype object's @@unscopables property 
> PASS AnimationTimeline interface: attribute currentTime 
>-PASS Unscopable handled correctly for currentTime property on AnimationTimeline 
> PASS DocumentTimeline interface: existence and properties of interface object 
> PASS DocumentTimeline interface object length 
> PASS DocumentTimeline interface object name 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/idlharness-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/idlharness-expected.txt
>index eaded068ed38c69ebb383c83abd9d9c7219b2287..4e02d282d6cf0432fbceac5a631c9829cc6e0526 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/idlharness-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/idlharness-expected.txt
>@@ -6,9 +6,7 @@ PASS AnimationEffectReadOnly interface: existence and properties of interface pr
> PASS AnimationEffectReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS AnimationEffectReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS AnimationEffectReadOnly interface: attribute timing 
>-PASS Unscopable handled correctly for timing property on AnimationEffectReadOnly 
> PASS AnimationEffectReadOnly interface: operation getComputedTiming() 
>-PASS Unscopable handled correctly for getComputedTiming() on AnimationEffectReadOnly 
> PASS KeyframeEffectReadOnly interface: existence and properties of interface object 
> PASS KeyframeEffectReadOnly interface object length 
> PASS KeyframeEffectReadOnly interface object name 
>@@ -16,13 +14,9 @@ PASS KeyframeEffectReadOnly interface: existence and properties of interface pro
> PASS KeyframeEffectReadOnly interface: existence and properties of interface prototype object's "constructor" property 
> PASS KeyframeEffectReadOnly interface: existence and properties of interface prototype object's @@unscopables property 
> PASS KeyframeEffectReadOnly interface: attribute target 
>-PASS Unscopable handled correctly for target property on KeyframeEffectReadOnly 
> PASS KeyframeEffectReadOnly interface: attribute iterationComposite 
>-PASS Unscopable handled correctly for iterationComposite property on KeyframeEffectReadOnly 
> PASS KeyframeEffectReadOnly interface: attribute composite 
>-PASS Unscopable handled correctly for composite property on KeyframeEffectReadOnly 
> PASS KeyframeEffectReadOnly interface: operation getKeyframes() 
>-PASS Unscopable handled correctly for getKeyframes() on KeyframeEffectReadOnly 
> PASS KeyframeEffectReadOnly must be primary interface of new KeyframeEffectReadOnly(null, null) 
> PASS Stringification of new KeyframeEffectReadOnly(null, null) 
> PASS KeyframeEffectReadOnly interface: new KeyframeEffectReadOnly(null, null) must inherit property "target" with the proper type 
>@@ -38,13 +32,9 @@ PASS KeyframeEffect interface: existence and properties of interface prototype o
> PASS KeyframeEffect interface: existence and properties of interface prototype object's "constructor" property 
> PASS KeyframeEffect interface: existence and properties of interface prototype object's @@unscopables property 
> PASS KeyframeEffect interface: attribute target 
>-PASS Unscopable handled correctly for target property on KeyframeEffect 
> PASS KeyframeEffect interface: attribute iterationComposite 
>-PASS Unscopable handled correctly for iterationComposite property on KeyframeEffect 
> PASS KeyframeEffect interface: attribute composite 
>-PASS Unscopable handled correctly for composite property on KeyframeEffect 
> PASS KeyframeEffect interface: operation setKeyframes(object) 
>-PASS Unscopable handled correctly for setKeyframes(object) on KeyframeEffect 
> PASS KeyframeEffect must be primary interface of new KeyframeEffect(null, null) 
> PASS Stringification of new KeyframeEffect(null, null) 
> PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "target" with the proper type

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Attachments on bug 189303: 348908 | 348918 | 348920 | 348922 | 348924 | 348928 | 348939 | 348940 | 348941 | 348944 | 349009 | 349011 | 349013 | 349014 | 349015 | 349017 | 349018 | 349019 | 349025 | 349031 | 349036 | 349037 | 349062 | 349126 | 349129 | 349130 | 349133