Attachment 372999 Details for Bug 188043 – Patch

[patch] Patch

0001-Bug-188043-Add-support-for-ScrollOptions-ScrollBehav.patch (text/plain), 133.38 KB, created by Frédéric Wang (:fredw) on 2019-06-26 20:58:08 PDT

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Creator: Frédéric Wang (:fredw)

Created: 2019-06-26 20:58:08 PDT

Size: 133.38 KB

patch

obsolete

>From 88a2aee734829c70d95825b7ecb5d82b1772f015 Mon Sep 17 00:00:00 2001
>From: Frederic Wang <fwang@igalia.com>
>Date: Tue, 25 Jun 2019 11:20:52 +0200
>Subject: [PATCH xserver] Bug 188043 - Add support for ScrollOptions'
> ScrollBehavior and CSS scroll-behavior properties
>
>---
> LayoutTests/ChangeLog                         |  10 ++
> LayoutTests/imported/w3c/ChangeLog            |  25 +++
> .../scroll-behavior-default-css-expected.txt  |   2 +-
> .../scroll-behavior-default-css.html          |   2 +-
> .../scroll-behavior-element-expected.txt      |  32 ++--
> .../cssom-view/scroll-behavior-element.html   |   2 +-
> ...roll-behavior-main-frame-root-expected.txt |  32 ++--
> .../scroll-behavior-main-frame-root.html      |   2 +-
> ...ll-behavior-main-frame-window-expected.txt |  24 +--
> .../scroll-behavior-main-frame-window.html    |   2 +-
> ...ehavior-scrollintoview-nested-expected.txt |   4 +-
> ...scroll-behavior-scrollintoview-nested.html |   2 +-
> .../scroll-behavior-smooth-positions.html     |   2 +-
> ...scroll-behavior-subframe-root-expected.txt |  32 ++--
> .../scroll-behavior-subframe-root.html        |   2 +-
> ...roll-behavior-subframe-window-expected.txt |  24 +--
> .../scroll-behavior-subframe-window.html      |   2 +-
> LayoutTests/platform/mac-wk1/TestExpectations |   6 +
> Source/WebCore/CMakeLists.txt                 |   2 +
> Source/WebCore/ChangeLog                      | 145 ++++++++++++++++++
> Source/WebCore/DerivedSources.make            |   2 +
> Source/WebCore/Headers.cmake                  |   2 +
> Source/WebCore/Sources.txt                    |   4 +
> Source/WebCore/SourcesGTK.txt                 |   1 -
> .../WebCore/WebCore.xcodeproj/project.pbxproj |  28 ++++
> .../css/CSSComputedStyleDeclaration.cpp       |   7 +
> Source/WebCore/css/CSSProperties.json         |  16 ++
> Source/WebCore/css/CSSValueKeywords.in        |   4 +
> Source/WebCore/css/StyleBuilderConverter.h    |   6 +
> .../WebCore/css/parser/CSSParserContext.cpp   |   2 +
> Source/WebCore/css/parser/CSSParserContext.h  |   4 +-
> .../WebCore/css/parser/CSSParserFastPaths.cpp |   5 -
> .../WebCore/css/parser/CSSPropertyParser.cpp  |  12 ++
> Source/WebCore/dom/Element.cpp                |  29 +++-
> Source/WebCore/page/DOMWindow.cpp             |  14 +-
> Source/WebCore/page/ScrollBehavior.cpp        |  48 ++++++
> Source/WebCore/page/ScrollBehavior.h          |  34 ++++
> Source/WebCore/page/ScrollBehavior.idl        |  20 +++
> Source/WebCore/page/ScrollIntoViewOptions.h   |   5 +-
> Source/WebCore/page/ScrollIntoViewOptions.idl |   3 +-
> Source/WebCore/page/ScrollOptions.h           |  30 ++++
> Source/WebCore/page/ScrollOptions.idl         |  22 +++
> Source/WebCore/page/ScrollToOptions.h         |  13 +-
> Source/WebCore/page/ScrollToOptions.idl       |   3 +-
> Source/WebCore/page/Settings.yaml             |   3 +
> Source/WebCore/platform/ScrollAnimation.h     |   3 +
> .../platform/ScrollAnimationKinetic.cpp       |   5 +
> .../WebCore/platform/ScrollAnimationKinetic.h |   1 +
> .../platform/ScrollAnimationSmooth.cpp        |  26 +++-
> .../WebCore/platform/ScrollAnimationSmooth.h  |   8 +-
> Source/WebCore/platform/ScrollAnimator.cpp    |  48 ++++++
> Source/WebCore/platform/ScrollAnimator.h      |  15 +-
> Source/WebCore/platform/ScrollView.cpp        |   6 +-
> Source/WebCore/platform/ScrollableArea.cpp    |  11 ++
> Source/WebCore/platform/ScrollableArea.h      |   2 +
> .../WebCore/platform/mac/ScrollAnimatorMac.mm |   1 +
> Source/WebCore/rendering/RenderBox.cpp        |   8 +
> Source/WebCore/rendering/RenderBox.h          |   1 +
> Source/WebCore/rendering/RenderLayer.cpp      |  39 ++++-
> Source/WebCore/rendering/RenderLayer.h        |   3 +
> Source/WebCore/rendering/style/RenderStyle.h  |   6 +
> .../style/StyleRareNonInheritedData.cpp       |   3 +
> .../style/StyleRareNonInheritedData.h         |   2 +
> Source/WebCore/testing/Internals.cpp          |   2 +-
> Source/WebKit/ChangeLog                       |  11 ++
> Source/WebKit/Shared/WebPreferences.yaml      |   8 +-
> Source/WebKitLegacy/mac/ChangeLog             |  17 ++
> .../mac/WebView/WebPreferenceKeysPrivate.h    |   1 +
> .../mac/WebView/WebPreferences.mm             |  11 ++
> .../mac/WebView/WebPreferencesPrivate.h       |   1 +
> Source/WebKitLegacy/mac/WebView/WebView.mm    |   1 +
> Source/WebKitLegacy/win/ChangeLog             |  17 ++
> .../win/Interfaces/IWebPreferencesPrivate.idl |   2 +
> .../win/WebPreferenceKeysPrivate.h            |   1 +
> Source/WebKitLegacy/win/WebPreferences.cpp    |  16 ++
> Source/WebKitLegacy/win/WebPreferences.h      |   2 +
> Source/WebKitLegacy/win/WebView.cpp           |   5 +
> Tools/ChangeLog                               |  11 ++
> Tools/DumpRenderTree/TestOptions.cpp          |   2 +
> Tools/DumpRenderTree/TestOptions.h            |   1 +
> Tools/DumpRenderTree/mac/DumpRenderTree.mm    |   1 +
> 81 files changed, 837 insertions(+), 132 deletions(-)
> create mode 100644 Source/WebCore/page/ScrollBehavior.cpp
> create mode 100644 Source/WebCore/page/ScrollBehavior.h
> create mode 100644 Source/WebCore/page/ScrollBehavior.idl
> create mode 100644 Source/WebCore/page/ScrollOptions.h
> create mode 100644 Source/WebCore/page/ScrollOptions.idl
>
>diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
>index 8a9fa8f70b0..a9f7bdc5842 100644
>--- a/LayoutTests/ChangeLog
>+++ b/LayoutTests/ChangeLog
>@@ -1,3 +1,13 @@
>+2018-11-07  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * platform/mac-wk1/TestExpectations: Skip these tests on WK1 as they don't work for now and
>+        are slow anyway.
>+
> 2019-06-24  Wenson Hsieh  <wenson_hsieh@apple.com>
> 
>         [Text autosizing] [iPadOS] Revise our heuristics to determine idempotent text autosizing candidates
>diff --git a/LayoutTests/imported/w3c/ChangeLog b/LayoutTests/imported/w3c/ChangeLog
>index 3d32170ae4e..9e791c333ca 100644
>--- a/LayoutTests/imported/w3c/ChangeLog
>+++ b/LayoutTests/imported/w3c/ChangeLog
>@@ -1,3 +1,28 @@
>+2018-11-06  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Enable CSSOMViewSmoothScrollingEnabled on scroll behavior tests and update expectations.
>+
>+        * web-platform-tests/css/cssom-view/scroll-behavior-default-css-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-default-css.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-element-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-element.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-subframe-root-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-subframe-window-expected.txt:
>+        * web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html:
>+
> 2019-06-24  Antoine Quint  <graouts@apple.com>
> 
>         [Pointer Events WPT] Unskip imported/w3c/web-platform-tests/pointerevents/pointerlock/pointerevent_coordinates_when_locked.html
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css-expected.txt
>index 9068b797552..8d4ca64155f 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css-expected.txt
>@@ -1,4 +1,4 @@
> 
> PASS Instant scrolling of an element with default scroll-behavior 
>-FAIL Smooth scrolling of an element with default scroll-behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Smooth scrolling of an element with default scroll-behavior 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css.html
>index 8606b1f3ed4..eed63a06932 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing default value of scroll-behavior</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element-expected.txt
>index 2b9129c1cf4..53a961ef56a 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element-expected.txt
>@@ -2,35 +2,35 @@
> PASS Element with auto scroll-behavior ; scroll() with default behavior 
> PASS Element with auto scroll-behavior ; scroll() with auto behavior 
> PASS Element with auto scroll-behavior ; scroll() with instant behavior 
>-FAIL Element with auto scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scroll() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scroll() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with auto scroll-behavior ; scroll() with smooth behavior 
>+PASS Element with smooth scroll-behavior ; scroll() with default behavior 
>+PASS Element with smooth scroll-behavior ; scroll() with auto behavior 
> PASS Element with smooth scroll-behavior ; scroll() with instant behavior 
>-FAIL Element with smooth scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with smooth scroll-behavior ; scroll() with smooth behavior 
> PASS Element with auto scroll-behavior ; scrollTo() with default behavior 
> PASS Element with auto scroll-behavior ; scrollTo() with auto behavior 
> PASS Element with auto scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Element with auto scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollTo() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollTo() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with auto scroll-behavior ; scrollTo() with smooth behavior 
>+PASS Element with smooth scroll-behavior ; scrollTo() with default behavior 
>+PASS Element with smooth scroll-behavior ; scrollTo() with auto behavior 
> PASS Element with smooth scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Element with smooth scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with smooth scroll-behavior ; scrollTo() with smooth behavior 
> PASS Element with auto scroll-behavior ; scrollBy() with default behavior 
> PASS Element with auto scroll-behavior ; scrollBy() with auto behavior 
> PASS Element with auto scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Element with auto scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollBy() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollBy() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with auto scroll-behavior ; scrollBy() with smooth behavior 
>+PASS Element with smooth scroll-behavior ; scrollBy() with default behavior 
>+PASS Element with smooth scroll-behavior ; scrollBy() with auto behavior 
> PASS Element with smooth scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Element with smooth scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with smooth scroll-behavior ; scrollBy() with smooth behavior 
> PASS Element with auto scroll-behavior ; scrollIntoView() with default behavior 
> PASS Element with auto scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Element with auto scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Element with auto scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollIntoView() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Element with smooth scroll-behavior ; scrollIntoView() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with auto scroll-behavior ; scrollIntoView() with smooth behavior 
>+PASS Element with smooth scroll-behavior ; scrollIntoView() with default behavior 
>+PASS Element with smooth scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Element with smooth scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Element with smooth scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Element with smooth scroll-behavior ; scrollIntoView() with smooth behavior 
> PASS Aborting an ongoing smooth scrolling on an element with another smooth scrolling 
> PASS Aborting an ongoing smooth scrolling on an element with an instant scrolling 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html
>index 9f60ca77112..556b66c824f 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior for Element.scroll* and scroll-behavior on an element</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root-expected.txt
>index d922258af27..97caea27bb5 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root-expected.txt
>@@ -3,35 +3,35 @@ PASS Page loaded
> PASS Main frame with auto scroll-behavior ; scroll() with default behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scroll() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scroll() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scroll() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scroll() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scrollTo() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scrollBy() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollIntoView() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollIntoView() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollIntoView() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scrollIntoView() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollIntoView() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scrollIntoView() with smooth behavior 
> PASS Aborting an ongoing smooth scrolling on the main frame with another smooth scrolling 
> PASS Aborting an ongoing smooth scrolling on the main frame with an instant scrolling 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html
>index 7ef0a4aa0da..188863ff82c 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior for Element.scroll* and scroll-behavior on the root of the main frame</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window-expected.txt
>index c6be96661c2..382385aab49 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window-expected.txt
>@@ -3,27 +3,27 @@ PASS Page loaded
> PASS Main frame with auto scroll-behavior ; scroll() with default behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scroll() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scroll() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scroll() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scroll() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scrollTo() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with auto scroll-behavior ; scrollBy() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 2430 but got 2430
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior 
> PASS Aborting an ongoing smooth scrolling on the main frame with another smooth scrolling 
> PASS Aborting an ongoing smooth scrolling on the main frame with an instant scrolling 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html
>index 57b0d913461..23e298dfdf0 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior for Element.scroll* on the window of the main frame</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested-expected.txt
>index 7ce10c08961..a3a51d3e6ab 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested-expected.txt
>@@ -1,3 +1,5 @@
> 
>-FAIL scrollIntoView with nested elements with different scroll-behavior assert_less_than: Element with smooth behavior should not scroll immediately expected a number less than 500 but got 500
>+FAIL scrollIntoView with nested elements with different scroll-behavior assert_equals: Element with instant behavior should jump to the final position expected 0 but got 1000
>+
>+assert_equals: Element with instant behavior should jump to the final position expected 500 but got 1000
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html
>index 2a97e065663..ece539b3352 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior with scrollIntoView for nested scrolling nodes</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html
>index 19e317d5e4b..b610a47b5c7 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scroll positions when scrolling an element with smooth behavior</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root-expected.txt
>index b6fa1c2ec8b..2799fdcc29e 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root-expected.txt
>@@ -3,35 +3,35 @@ PASS iframe loaded
> PASS Subframe with auto scroll-behavior ; scroll() with default behavior 
> PASS Subframe with auto scroll-behavior ; scroll() with auto behavior 
> PASS Subframe with auto scroll-behavior ; scroll() with instant behavior 
>-FAIL Subframe with auto scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scroll() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scroll() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with auto scroll-behavior ; scroll() with smooth behavior 
>+PASS Subframe with smooth scroll-behavior ; scroll() with default behavior 
>+PASS Subframe with smooth scroll-behavior ; scroll() with auto behavior 
> PASS Subframe with smooth scroll-behavior ; scroll() with instant behavior 
>-FAIL Subframe with smooth scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with smooth scroll-behavior ; scroll() with smooth behavior 
> PASS Subframe with auto scroll-behavior ; scrollTo() with default behavior 
> PASS Subframe with auto scroll-behavior ; scrollTo() with auto behavior 
> PASS Subframe with auto scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Subframe with auto scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollTo() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollTo() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with auto scroll-behavior ; scrollTo() with smooth behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollTo() with default behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollTo() with auto behavior 
> PASS Subframe with smooth scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Subframe with smooth scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with smooth scroll-behavior ; scrollTo() with smooth behavior 
> PASS Subframe with auto scroll-behavior ; scrollBy() with default behavior 
> PASS Subframe with auto scroll-behavior ; scrollBy() with auto behavior 
> PASS Subframe with auto scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Subframe with auto scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollBy() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollBy() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with auto scroll-behavior ; scrollBy() with smooth behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollBy() with default behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollBy() with auto behavior 
> PASS Subframe with smooth scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Subframe with smooth scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with smooth scroll-behavior ; scrollBy() with smooth behavior 
> PASS Subframe with auto scroll-behavior ; scrollIntoView() with default behavior 
> PASS Subframe with auto scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Subframe with auto scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Subframe with auto scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollIntoView() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Subframe with smooth scroll-behavior ; scrollIntoView() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with auto scroll-behavior ; scrollIntoView() with smooth behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollIntoView() with default behavior 
>+PASS Subframe with smooth scroll-behavior ; scrollIntoView() with auto behavior 
> PASS Subframe with smooth scroll-behavior ; scrollIntoView() with instant behavior 
>-FAIL Subframe with smooth scroll-behavior ; scrollIntoView() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Subframe with smooth scroll-behavior ; scrollIntoView() with smooth behavior 
> PASS Aborting an ongoing smooth scrolling on a subframe with another smooth scrolling 
> PASS Aborting an ongoing smooth scrolling on a subframe with an instant scrolling 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html
>index 32de1b62038..d36c9d03bff 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior for Element.scroll* and scroll-behavior on the root of a subframe</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window-expected.txt
>index cc665ebdb8b..05eb3272f40 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window-expected.txt
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window-expected.txt
>@@ -3,27 +3,27 @@ PASS iframe loaded
> PASS Main frame with auto scroll-behavior ; scroll() with default behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scroll() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scroll() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with auto scroll-behavior ; scroll() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scroll() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scroll() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scroll() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with smooth scroll-behavior ; scroll() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with auto scroll-behavior ; scrollTo() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollTo() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with smooth scroll-behavior ; scrollTo() with smooth behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with default behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with auto scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with auto scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with default behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with auto behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with auto scroll-behavior ; scrollBy() with smooth behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with default behavior 
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with auto behavior 
> PASS Main frame with smooth scroll-behavior ; scrollBy() with instant behavior 
>-FAIL Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior assert_less_than: Should not set scrollLeft immediately expected a number less than 500 but got 500
>+PASS Main frame with smooth scroll-behavior ; scrollBy() with smooth behavior 
> PASS Aborting an ongoing smooth scrolling on the main frame with another smooth scrolling 
> PASS Aborting an ongoing smooth scrolling on the main frame with an instant scrolling 
> 
>diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html
>index 0a8ed39d1b9..74aec5467ff 100644
>--- a/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html
>+++ b/LayoutTests/imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html
>@@ -1,4 +1,4 @@
>-<!DOCTYPE html>
>+<!DOCTYPE html>
> <title>Testing scrollOptions' behavior for Element.scroll* and scroll-behavior on the root of a subframe</title>
> <meta name="timeout" content="long"/>
> <link rel="author" title="FrÃ©dÃ©ric Wang" href="mailto:fwang@igalia.com">
>diff --git a/LayoutTests/platform/mac-wk1/TestExpectations b/LayoutTests/platform/mac-wk1/TestExpectations
>index a046f6afa0e..427dd752e34 100644
>--- a/LayoutTests/platform/mac-wk1/TestExpectations
>+++ b/LayoutTests/platform/mac-wk1/TestExpectations
>@@ -694,6 +694,12 @@ webkit.org/b/189594 imported/w3c/web-platform-tests/css/css-animations/pending-s
> 
> webkit.org/b/188070 imported/w3c/web-platform-tests/streams/piping/error-propagation-backward.html [ Pass Failure ]
> 
>+# Tests for smooth scroll behavior do not all work and they are slow, so let's just skip them.
>+webkit.org/b/191357 imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html [ Skip ]
>+webkit.org/b/191357 imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html [ Skip ]
>+webkit.org/b/191357 imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html [ Skip ]
>+webkit.org/b/191357 imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html [ Skip ]
>+
> webkit.org/b/189908 imported/w3c/web-platform-tests/resource-timing/resource_timing.worker.html [ Failure ]
> 
> webkit.org/b/189756 [ Mojave+ ] compositing/filters/opacity-change-on-filtered-paints-into-ancestor.html [ Pass ImageOnlyFailure ]
>diff --git a/Source/WebCore/CMakeLists.txt b/Source/WebCore/CMakeLists.txt
>index 9cae1b7f47b..e4019c80372 100644
>--- a/Source/WebCore/CMakeLists.txt
>+++ b/Source/WebCore/CMakeLists.txt
>@@ -933,8 +933,10 @@ set(WebCore_NON_SVG_IDL_FILES
>     page/ResizeObserverCallback.idl
>     page/ResizeObserverEntry.idl
>     page/Screen.idl
>+    page/ScrollBehavior.idl
>     page/ScrollIntoViewOptions.idl
>     page/ScrollLogicalPosition.idl
>+    page/ScrollOptions.idl
>     page/ScrollToOptions.idl
>     page/ShareData.idl
>     page/UndoItem.idl
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index e54e326efc2..0ee54547403 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,148 @@
>+2018-11-09  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        This patch introduces a programmatic smooth scrolling in WebKit from the CSSOM View
>+        specification [1]. To use this effect, web developers can pass a behavior parameter (auto,
>+        smooth, or instant) to Element.scroll, Element.scrollTo, Element.scrollBy,
>+        Element.scrollIntoView, Window.scroll, Window.scrollTo or Window.scrollBy [2]. When behavior
>+        is auto, the instant/smooth characteristic is actually taken from the value of a new CSS
>+        scroll-behavior property [3]. Both the new CSS and DOM behavior are protected by a runtime
>+        flag. The Element.scrollIntoView part will be refined later in bug 189907. The actual
>+        animation relies on the existing ScrollAnimationSmooth.
>+
>+        [1] https://drafts.csswg.org/cssom-view
>+        [2] https://drafts.csswg.org/cssom-view/#dictdef-scrolloptions
>+        [3] https://drafts.csswg.org/cssom-view/#propdef-scroll-behavior
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+
>+        Tests: imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-default-css.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-element.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-root.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-main-frame-window.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-scrollintoview-nested.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-smooth-positions.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-root.html
>+               imported/w3c/web-platform-tests/css/cssom-view/scroll-behavior-subframe-window.html
>+
>+        * CMakeLists.txt: Add IDL files for ScrollOptions and ScrollBehavior.
>+        * DerivedSources.make: Ditto.
>+        * Sources.txt: Add ScrollBehavor and ScrollOptions implementation. Also build
>+        ScrollAnimationSmooth.cpp on all platforms.
>+        * Headers.cmake: Add headers for ScrollBehavor and ScrollOptions.
>+        * SourcesGTK.txt: Remove ScrollAnimationSmooth.cpp since it is built on all platforms now.
>+        * WebCore.xcodeproj/project.pbxproj: Add files to the build system.
>+        * css/CSSComputedStyleDeclaration.cpp: Handle scroll-behavior.
>+        (WebCore::ComputedStyleExtractor::valueForPropertyinStyle):
>+        * css/CSSProperties.json: Add scroll-behavior.
>+        * css/CSSValueKeywords.in: Add keywords for scroll-behavior.
>+        * css/StyleBuilderConverter.h:
>+        (WebCore::StyleBuilderConverter::convertSmoothScrolling): New function to convert
>+        scroll-behavior into a "is smooth" boolean.
>+        * css/parser/CSSParserContext.cpp: Add runtime config for scroll-behavior.
>+        (WebCore::CSSParserContext::CSSParserContext):
>+        (WebCore::operator==):
>+        * css/parser/CSSParserContext.h: Ditto.
>+        (WebCore::CSSParserContextHash::hash):
>+        * css/parser/CSSParserFastPaths.cpp: Remove scroll-behavior templates. It is handled in the
>+        slow path since property can be disabled.
>+        (WebCore::CSSParserFastPaths::isValidKeywordPropertyAndValue):
>+        (WebCore::CSSParserFastPaths::isKeywordPropertyID):
>+        * css/parser/CSSPropertyParser.cpp:
>+        (WebCore::CSSPropertyParser::parseSingleValue): Parse scroll-behavior (only if enabled).
>+        * dom/Element.cpp:
>+        (WebCore::Element::scrollIntoView): Pass scroll behavior, if any.
>+        (WebCore::Element::scrollBy): Use fromCoordinates helper function.
>+        (WebCore::Element::scrollTo): Handle the case when scroll behavior is smooth. Use
>+        fromCoordinates helper function.
>+        * page/DOMWindow.cpp:
>+        (WebCore::DOMWindow::scrollBy const): Use fromCoordinates helper function.
>+        (WebCore::DOMWindow::scrollTo const): Use fromCoordinates helper function. Handle the case
>+        when scroll behavior is smooth. The optimization when scroll position is (0, 0) is skipped
>+        when a scroll is in progress, otherwise such a scroll can't be cancelled by a follow-up
>+        scroll.
>+        * page/ScrollBehavior.cpp: Added.
>+        (WebCore::useSmoothScrolling): Helper funciton to determine the scroll behavior to apply to
>+        an element from the CSS and DOM behavior.
>+        * page/ScrollBehavior.h: Added.
>+        * page/ScrollBehavior.idl: Added.
>+        * page/ScrollIntoViewOptions.h: Make this class inherits from ScrollOption. Also remove
>+        unnecessary forward declaration.
>+        * page/ScrollIntoViewOptions.idl: Make this class inherits from ScrollOption.
>+        * page/ScrollOptions.h: Added.
>+        * page/ScrollOptions.idl: Added.
>+        * page/ScrollToOptions.h: Make this struct inherits from ScrollOptions.
>+        (WebCore::fromCoordinates): New helper function to generate a ScrollToOptions with undefined
>+        behavior. This is necessary to replace curly brace { x, y } declarations now that there is
>+        an extra behavior member from the parent class.
>+        (WebCore::normalizeNonFiniteCoordinatesOrFallBackTo): Copy the current ScrollToOptions so
>+        that the scroll behavior is preserved.
>+        * page/ScrollToOptions.idl: Make this class inherit from ScrollOptions.
>+        * page/Settings.yaml: New setting for CSSOM View smooth scrolling.
>+        * platform/ScrollAnimation.h:
>+        (WebCore::ScrollAnimation::scroll): Function to animate scrolling to a specified position.
>+        (WebCore::ScrollAnimation::isScrollInProgress const):
>+        * platform/ScrollAnimationKinetic.cpp:
>+        (WebCore::ScrollAnimationKinetic::isScrollInProgress const):
>+        * platform/ScrollAnimationKinetic.h:
>+        * platform/ScrollAnimationSmooth.cpp: Build this file on all platforms. Add a
>+        smoothFactorForProgrammaticScroll parameter to slow down the smooth scrolling.
>+        (WebCore::ScrollAnimationSmooth::scroll):
>+        (WebCore::ScrollAnimationSmooth::updatePerAxisData): Scale the time parameters of the
>+        animation so that it looks smoother.
>+        * platform/ScrollAnimationSmooth.h: Declare the class on all platforms.
>+        * platform/ScrollAnimator.cpp:
>+        (WebCore::ScrollAnimator::ScrollAnimator): Initialize animation member for programmatic scrolling.
>+        (WebCore::ScrollAnimator::isScrollInProgress const): For now, only claims scroll is in
>+        progress if smooth programmatic scroll is in progress.
>+        (WebCore::ScrollAnimator::scrollToOffset): Animate scrolling to the specified position.
>+        (WebCore::ScrollAnimator::cancelAnimations): Copy logic from ScrollAnimationSmooth.cpp.
>+        (WebCore::ScrollAnimator::serviceScrollAnimations): Ditto.
>+        (WebCore::ScrollAnimator::willEndLiveResize): Ditto.
>+        (WebCore::ScrollAnimator::didAddVerticalScrollbar): Ditto.
>+        (WebCore::ScrollAnimator::didAddHorizontalScrollbar): Ditto.
>+        * platform/ScrollAnimator.h: New animation member for smooth programmatic scrolling.
>+        * platform/ScrollAnimatorMac.mm:
>+        (WebCore::ScrollAnimatorMac::cancelAnimations): Call parent member to handle programmatic scrolling.
>+        * platform/ScrollView.cpp:
>+        (WebCore::ScrollView::setScrollPosition): Follow the CSSOM View spec: If a scroll is in
>+        progress, we interrupt it and continue the scroll call (even when we are at the final
>+        position).
>+        * platform/ScrollableArea.cpp:
>+        (WebCore::ScrollableArea::isScrollInProgress const): Helper function to check whether scroll
>+        is in progress on the animator. If m_scrollAnimator does not exist we don't construct it.
>+        (WebCore::ScrollableArea::scrollToOffsetWithAnimation):
>+        * platform/ScrollableArea.h:
>+        * rendering/RenderBox.cpp:
>+        (WebCore::RenderBox::scrollToPositionWithAnimation): Similar to setScrollTop/setScrollLeft
>+        but animate the scrolling.
>+        * rendering/RenderBox.h:
>+        * rendering/RenderLayer.cpp:
>+        (WebCore::RenderLayer::scrollToOffset): Follow the CSSOM View spec: If a scroll is in
>+        progress, we interrupt it and continue the scroll call (even when we are at the final
>+        position).
>+        (WebCore::RenderLayer::scrollToOffsetWithAnimation): Ditto. This is similar to scrollToOffset
>+        but animates the scroll.
>+        (WebCore::RenderLayer::scrollRectToVisible): Again don't do an early return if scroll is in
>+        progress. We call scrollToOffsetWithAnimation instead of scrollToOffset when appropriate.
>+        Note that this function may not work well for several nested scroll boxes with at least one
>+        element with smooth behavior. It will handled in bug Follow.
>+        * rendering/RenderLayer.h: Add scroll behavior to ScrollTectToVisibleOptions.
>+        * rendering/style/RenderStyle.h: Handle 'smooth scrolling' boolean data.
>+        (WebCore::RenderStyle::useSmoothScrolling const):
>+        (WebCore::RenderStyle::setUseSmoothScrolling):
>+        (WebCore::RenderStyle::initialUseSmoothScrolling):
>+        * rendering/style/StyleRareNonInheritedData.cpp: Ditto.
>+        (WebCore::StyleRareNonInheritedData::StyleRareNonInheritedData):
>+        (WebCore::StyleRareNonInheritedData::operator== const):
>+        * rendering/style/StyleRareNonInheritedData.h: Ditto.
>+        * testing/Internals.cpp:
>+        (WebCore::Internals::unconstrainedScrollTo): Use fromCoordinates helper function.
>+
> 2019-06-24  Wenson Hsieh  <wenson_hsieh@apple.com>
> 
>         [Text autosizing] [iPadOS] Revise our heuristics to determine idempotent text autosizing candidates
>diff --git a/Source/WebCore/DerivedSources.make b/Source/WebCore/DerivedSources.make
>index d88aed458f0..1c0230b1bd2 100644
>--- a/Source/WebCore/DerivedSources.make
>+++ b/Source/WebCore/DerivedSources.make
>@@ -879,8 +879,10 @@ JS_BINDING_IDLS = \
>     $(WebCore)/page/ResizeObserverCallback.idl \
>     $(WebCore)/page/ResizeObserverEntry.idl \
>     $(WebCore)/page/Screen.idl \
>+    $(WebCore)/page/ScrollBehavior.idl \
>     $(WebCore)/page/ScrollIntoViewOptions.idl \
>     $(WebCore)/page/ScrollLogicalPosition.idl \
>+    $(WebCore)/page/ScrollOptions.idl \
>     $(WebCore)/page/ScrollToOptions.idl \
>     $(WebCore)/page/ShareData.idl \
>     $(WebCore)/page/UndoItem.idl \
>diff --git a/Source/WebCore/Headers.cmake b/Source/WebCore/Headers.cmake
>index a81d82ab8df..e41ef886153 100644
>--- a/Source/WebCore/Headers.cmake
>+++ b/Source/WebCore/Headers.cmake
>@@ -805,8 +805,10 @@ set(WebCore_PRIVATE_FRAMEWORK_HEADERS
>     page/RemoteFrame.h
>     page/RenderingUpdateScheduler.h
>     page/RuntimeEnabledFeatures.h
>+    page/ScrollBehavior.h
>     page/ScrollIntoViewOptions.h
>     page/ScrollLogicalPosition.h
>+    page/ScrollOptions.h
>     page/ScrollToOptions.h
>     page/SecurityOrigin.h
>     page/SecurityOriginData.h
>diff --git a/Source/WebCore/Sources.txt b/Source/WebCore/Sources.txt
>index 155c66139b5..dc9ca598e67 100644
>--- a/Source/WebCore/Sources.txt
>+++ b/Source/WebCore/Sources.txt
>@@ -1554,6 +1554,7 @@ page/ResourceUsageOverlay.cpp
> page/ResourceUsageThread.cpp
> page/RuntimeEnabledFeatures.cpp
> page/Screen.cpp
>+page/ScrollBehavior.cpp
> page/SecurityOrigin.cpp
> page/SecurityOriginData.cpp
> page/SecurityPolicy.cpp
>@@ -1657,6 +1658,7 @@ platform/RuntimeApplicationChecks.cpp
> platform/SSLKeyGenerator.cpp
> platform/SchemeRegistry.cpp
> platform/ScrollAnimator.cpp
>+platform/ScrollAnimationSmooth.cpp
> platform/ScrollView.cpp
> platform/ScrollableArea.cpp
> platform/Scrollbar.cpp
>@@ -3237,8 +3239,10 @@ JSSVGZoomEvent.cpp
> JSScreen.cpp
> JSScreenLuminance.cpp
> JSScriptProcessorNode.cpp
>+JSScrollBehavior.cpp
> JSScrollIntoViewOptions.cpp
> JSScrollLogicalPosition.cpp
>+JSScrollOptions.cpp
> JSScrollToOptions.cpp
> JSSecurityPolicyViolationEvent.cpp
> JSServiceWorker.cpp
>diff --git a/Source/WebCore/SourcesGTK.txt b/Source/WebCore/SourcesGTK.txt
>index 33430f903c8..81a91c77b31 100644
>--- a/Source/WebCore/SourcesGTK.txt
>+++ b/Source/WebCore/SourcesGTK.txt
>@@ -60,7 +60,6 @@ page/scrolling/nicosia/ScrollingTreeStickyNode.cpp
> page/scrolling/generic/ScrollingThreadGeneric.cpp
> 
> platform/ScrollAnimationKinetic.cpp
>-platform/ScrollAnimationSmooth.cpp
> platform/UserAgentQuirks.cpp
> 
> platform/generic/ScrollAnimatorGeneric.cpp
>diff --git a/Source/WebCore/WebCore.xcodeproj/project.pbxproj b/Source/WebCore/WebCore.xcodeproj/project.pbxproj
>index ae4802efa5b..cde7690003a 100644
>--- a/Source/WebCore/WebCore.xcodeproj/project.pbxproj
>+++ b/Source/WebCore/WebCore.xcodeproj/project.pbxproj
>@@ -2406,6 +2406,8 @@
> 		83407FC11E8D9C1700E048D3 /* VisibilityChangeClient.h in Headers */ = {isa = PBXBuildFile; fileRef = 83407FC01E8D9C1200E048D3 /* VisibilityChangeClient.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		834476EF1DA5BC5E002B5EB0 /* JSScrollLogicalPosition.h in Headers */ = {isa = PBXBuildFile; fileRef = 83E9B3011DA5A51E00FFD8D4 /* JSScrollLogicalPosition.h */; };
> 		834476EF1DA5BC5E002B5EC1 /* JSScrollIntoViewOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 83E9B3011DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.h */; };
>+		834476EF1DA5BC5E002B6EB0 /* JSScrollBehavior.h in Headers */ = {isa = PBXBuildFile; fileRef = 83E9B3011DA5A51E00FFE8D4 /* JSScrollBehavior.h */; };
>+		834476EF1DA5BC5E002B6EC1 /* JSScrollOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 83E9B3011DA5A51E00FFE8E5 /* JSScrollOptions.h */; };
> 		834476EF1DA5BC5E002B6ED2 /* JSScrollToOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 83E9B3011DA5A51E00FFE8F6 /* JSScrollToOptions.h */; };
> 		8348BFAC1B85729800912F36 /* ClassCollection.h in Headers */ = {isa = PBXBuildFile; fileRef = 8348BFAA1B85729500912F36 /* ClassCollection.h */; };
> 		834DFAD01F7DAE5D00C2725B /* SharedStringHash.h in Headers */ = {isa = PBXBuildFile; fileRef = 834DFACC1F7DAE5600C2725B /* SharedStringHash.h */; settings = {ATTRIBUTES = (Private, ); }; };
>@@ -2461,6 +2463,8 @@
> 		83C45B8E1DC2B68A008871BA /* ValidationBubble.h in Headers */ = {isa = PBXBuildFile; fileRef = 83C45B8D1DC2B67C008871BA /* ValidationBubble.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		83C5795D1DA5C301006F9C86 /* ScrollLogicalPosition.h in Headers */ = {isa = PBXBuildFile; fileRef = 8350C3E71DA59B6200355424 /* ScrollLogicalPosition.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		83C5795D1DA5C301006F9C97 /* ScrollIntoViewOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 8350C3E71DA59B6200355435 /* ScrollIntoViewOptions.h */; settings = {ATTRIBUTES = (Private, ); }; };
>+		83C5795D1DA5C301006FAC86 /* ScrollBehavior.h in Headers */ = {isa = PBXBuildFile; fileRef = 8350C3E71DA59B6200356424 /* ScrollBehavior.h */; settings = {ATTRIBUTES = (Private, ); }; };
>+		83C5795D1DA5C301006FAC97 /* ScrollOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 8350C3E71DA59B6200356435 /* ScrollOptions.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		83C5795D1DA5C301006FACA8 /* ScrollToOptions.h in Headers */ = {isa = PBXBuildFile; fileRef = 8350C3E71DA59B6200356446 /* ScrollToOptions.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		83D35AEC1C7187FA00F70D5A /* XMLHttpRequestEventTarget.h in Headers */ = {isa = PBXBuildFile; fileRef = 83D35AEA1C7187ED00F70D5A /* XMLHttpRequestEventTarget.h */; };
> 		83D35AF21C718D9000F70D5A /* JSXMLHttpRequestEventTarget.h in Headers */ = {isa = PBXBuildFile; fileRef = 83D35AF01C718D8400F70D5A /* JSXMLHttpRequestEventTarget.h */; };
>@@ -10037,6 +10041,12 @@
> 		834DFACE1F7DAE5700C2725B /* SharedStringHash.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = SharedStringHash.cpp; sourceTree = "<group>"; };
> 		8350C3E71DA59B6200355424 /* ScrollLogicalPosition.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollLogicalPosition.h; sourceTree = "<group>"; };
> 		8350C3E71DA59B6200355435 /* ScrollIntoViewOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollIntoViewOptions.h; sourceTree = "<group>"; };
>+		8350C3E81DA59B6200355435 /* ScrollIntoViewOptions.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = ScrollIntoViewOptions.idl; sourceTree = "<group>"; };
>+		8350C3E71DA59B6200356424 /* ScrollBehavior.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollBehavior.h; sourceTree = "<group>"; };
>+		8350C3E71DA59B6200356434 /* ScrollBehavior.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollBehavior.cpp; sourceTree = "<group>"; };
>+		8350C3E81DA59B6200356424 /* ScrollBehavior.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = ScrollBehavior.idl; sourceTree = "<group>"; };
>+		8350C3E71DA59B6200356435 /* ScrollOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollOptions.h; sourceTree = "<group>"; };
>+		8350C3E81DA59B6200356435 /* ScrollOptions.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = ScrollOptions.idl; sourceTree = "<group>"; };
> 		8350C3E71DA59B6200356446 /* ScrollToOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ScrollToOptions.h; sourceTree = "<group>"; };
> 		8350C3E81DA59B6200355424 /* ScrollLogicalPosition.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = ScrollLogicalPosition.idl; sourceTree = "<group>"; };
> 		8350C3E81DA59B6200355435 /* ScrollIntoViewOptions.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = ScrollIntoViewOptions.idl; sourceTree = "<group>"; };
>@@ -10158,6 +10168,11 @@
> 		83E959E11B8BC22B004D9385 /* NativeNodeFilter.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = NativeNodeFilter.h; sourceTree = "<group>"; };
> 		83E9B3001DA5A51E00FFD8D4 /* JSScrollLogicalPosition.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSScrollLogicalPosition.cpp; sourceTree = "<group>"; };
> 		83E9B3001DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSScrollIntoViewOptions.cpp; sourceTree = "<group>"; };
>+		83E9B3011DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSScrollIntoViewOptions.h; sourceTree = "<group>"; };
>+		83E9B3001DA5A51E00FFE8D4 /* JSScrollBehavior.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSScrollBehavior.cpp; sourceTree = "<group>"; };
>+		83E9B3011DA5A51E00FFE8D4 /* JSScrollBehavior.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSScrollBehavior.h; sourceTree = "<group>"; };
>+		83E9B3001DA5A51E00FFE8E5 /* JSScrollOptions.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSScrollOptions.cpp; sourceTree = "<group>"; };
>+		83E9B3011DA5A51E00FFE8E5 /* JSScrollOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSScrollOptions.h; sourceTree = "<group>"; };
> 		83E9B3001DA5A51E00FFE8F6 /* JSScrollToOptions.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSScrollToOptions.cpp; sourceTree = "<group>"; };
> 		83E9B3011DA5A51E00FFD8D4 /* JSScrollLogicalPosition.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSScrollLogicalPosition.h; sourceTree = "<group>"; };
> 		83E9B3011DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSScrollIntoViewOptions.h; sourceTree = "<group>"; };
>@@ -20351,10 +20366,15 @@
> 				BCEC01BA0C274DAC009F4EC9 /* Screen.cpp */,
> 				BCEC01BB0C274DAC009F4EC9 /* Screen.h */,
> 				BCEC01BC0C274DAC009F4EC9 /* Screen.idl */,
>+				8350C3E71DA59B6200356434 /* ScrollBehavior.cpp */,
>+				8350C3E71DA59B6200356424 /* ScrollBehavior.h */,
>+				8350C3E81DA59B6200356424 /* ScrollBehavior.idl */,
> 				8350C3E71DA59B6200355435 /* ScrollIntoViewOptions.h */,
> 				8350C3E81DA59B6200355435 /* ScrollIntoViewOptions.idl */,
> 				8350C3E71DA59B6200355424 /* ScrollLogicalPosition.h */,
> 				8350C3E81DA59B6200355424 /* ScrollLogicalPosition.idl */,
>+				8350C3E71DA59B6200356435 /* ScrollOptions.h */,
>+				8350C3E81DA59B6200356435 /* ScrollOptions.idl */,
> 				8350C3E71DA59B6200356446 /* ScrollToOptions.h */,
> 				8350C3E81DA59B6200356446 /* ScrollToOptions.idl */,
> 				BCD0E0F70E972C3500265DEA /* SecurityOrigin.cpp */,
>@@ -25067,10 +25087,14 @@
> 				58B2FA022232D60A00938D63 /* JSResizeObserverEntry.h */,
> 				BCEC01C00C274DDD009F4EC9 /* JSScreen.cpp */,
> 				BCEC01C10C274DDD009F4EC9 /* JSScreen.h */,
>+				83E9B3001DA5A51E00FFE8D4 /* JSScrollBehavior.cpp */,
>+				83E9B3011DA5A51E00FFE8D4 /* JSScrollBehavior.h */,
> 				83E9B3001DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.cpp */,
> 				83E9B3011DA5A51E00FFD8E5 /* JSScrollIntoViewOptions.h */,
> 				83E9B3001DA5A51E00FFD8D4 /* JSScrollLogicalPosition.cpp */,
> 				83E9B3011DA5A51E00FFD8D4 /* JSScrollLogicalPosition.h */,
>+				83E9B3001DA5A51E00FFE8E5 /* JSScrollOptions.cpp */,
>+				83E9B3011DA5A51E00FFE8E5 /* JSScrollOptions.h */,
> 				83E9B3001DA5A51E00FFE8F6 /* JSScrollToOptions.cpp */,
> 				83E9B3011DA5A51E00FFE8F6 /* JSScrollToOptions.h */,
> 				7C73FB0F191EF6F4007DE061 /* JSUserMessageHandler.cpp */,
>@@ -30210,8 +30234,10 @@
> 				5E2C436C1BCF071E0001E2BC /* JSRTCTrackEvent.h in Headers */,
> 				BCEC01C30C274DDD009F4EC9 /* JSScreen.h in Headers */,
> 				FDA15ECE12B03F61003A583A /* JSScriptProcessorNode.h in Headers */,
>+				834476EF1DA5BC5E002B6EB0 /* JSScrollBehavior.h in Headers */,
> 				834476EF1DA5BC5E002B5EC1 /* JSScrollIntoViewOptions.h in Headers */,
> 				834476EF1DA5BC5E002B5EB0 /* JSScrollLogicalPosition.h in Headers */,
>+				834476EF1DA5BC5E002B6EC1 /* JSScrollOptions.h in Headers */,
> 				834476EF1DA5BC5E002B6ED2 /* JSScrollToOptions.h in Headers */,
> 				CED06AD11C77754800FDFAF1 /* JSSecurityPolicyViolationEvent.h in Headers */,
> 				5182C2561F3143CD0059BA7C /* JSServiceWorker.h in Headers */,
>@@ -31394,6 +31420,7 @@
> 				44C991860F3D1EBE00586670 /* ScrollbarThemeIOS.h in Headers */,
> 				BC8B853E0E7C7F1100AB6984 /* ScrollbarThemeMac.h in Headers */,
> 				0FE71406142170B800DB33BA /* ScrollbarThemeMock.h in Headers */,
>+				83C5795D1DA5C301006FAC86 /* ScrollBehavior.h in Headers */,
> 				1AA84F05143BA7BD0051D153 /* ScrollController.h in Headers */,
> 				0F605AED15F94848004DF0C0 /* ScrollingConstraints.h in Headers */,
> 				1AF62EE814DA22A70041556C /* ScrollingCoordinator.h in Headers */,
>@@ -31430,6 +31457,7 @@
> 				83C5795D1DA5C301006F9C97 /* ScrollIntoViewOptions.h in Headers */,
> 				7AAFE8D019CB8672000F56D8 /* ScrollLatchingState.h in Headers */,
> 				83C5795D1DA5C301006F9C86 /* ScrollLogicalPosition.h in Headers */,
>+				83C5795D1DA5C301006FAC97 /* ScrollOptions.h in Headers */,
> 				F478755419983AFF0024A287 /* ScrollSnapAnimatorState.h in Headers */,
> 				F46729281E0DE68500ACC3D8 /* ScrollSnapOffsetsInfo.h in Headers */,
> 				83C5795D1DA5C301006FACA8 /* ScrollToOptions.h in Headers */,
>diff --git a/Source/WebCore/css/CSSComputedStyleDeclaration.cpp b/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
>index aff6d3aba30..8ddd5315997 100644
>--- a/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
>+++ b/Source/WebCore/css/CSSComputedStyleDeclaration.cpp
>@@ -434,6 +434,9 @@ static const CSSPropertyID computedProperties[] = {
> #if ENABLE(OVERFLOW_SCROLLING_TOUCH)
>     CSSPropertyWebkitOverflowScrolling,
> #endif
>+    CSSPropertyScrollBehavior,
>+    CSSPropertyPerspective,
>+    CSSPropertyPerspectiveOrigin,
>     CSSPropertyWebkitPrintColorAdjust,
>     CSSPropertyWebkitRtlOrdering,
> #if ENABLE(TOUCH_EVENTS)
>@@ -3717,6 +3720,10 @@ RefPtr<CSSValue> ComputedStyleExtractor::valueForPropertyInStyle(const RenderSty
>                 return cssValuePool.createIdentifierValue(CSSValueAuto);
>             return cssValuePool.createIdentifierValue(CSSValueTouch);
> #endif
>+        case CSSPropertyScrollBehavior:
>+            if (!style.useSmoothScrolling())
>+                return cssValuePool.createIdentifierValue(CSSValueAuto);
>+            return cssValuePool.createIdentifierValue(CSSValueSmooth);
>         case CSSPropertyPerspective:
>             if (!style.hasPerspective())
>                 return cssValuePool.createIdentifierValue(CSSValueNone);
>diff --git a/Source/WebCore/css/CSSProperties.json b/Source/WebCore/css/CSSProperties.json
>index bcf161c01b4..f36ab8def54 100644
>--- a/Source/WebCore/css/CSSProperties.json
>+++ b/Source/WebCore/css/CSSProperties.json
>@@ -6492,6 +6492,22 @@
>                 "url": "https://www.w3.org/TR/css-ui-4/#propdef-user-select"
>             }
>         },
>+        "scroll-behavior": {
>+            "values": [
>+                "auto",
>+                "smooth"
>+            ],
>+            "codegen-properties": {
>+                "converter": "SmoothScrolling",
>+                "name-for-methods": "UseSmoothScrolling"
>+            },
>+            "status": {
>+                "status": "experimental"
>+            },
>+            "specification": {
>+                "url": "https://drafts.csswg.org/cssom-view/#propdef-scroll-behavior"
>+            }
>+        },
>         "scroll-padding": {
>             "codegen-properties": {
>                 "enable-if": "ENABLE_CSS_SCROLL_SNAP",
>diff --git a/Source/WebCore/css/CSSValueKeywords.in b/Source/WebCore/css/CSSValueKeywords.in
>index c4767f5a731..d4a50311381 100644
>--- a/Source/WebCore/css/CSSValueKeywords.in
>+++ b/Source/WebCore/css/CSSValueKeywords.in
>@@ -1384,6 +1384,10 @@ pan-y
> pinch-zoom
> #endif
> 
>+// scroll-behavior
>+// auto
>+smooth
>+
> // hanging-punctuation
> allow-end
> first
>diff --git a/Source/WebCore/css/StyleBuilderConverter.h b/Source/WebCore/css/StyleBuilderConverter.h
>index 69af5581565..adcceb5c9c4 100644
>--- a/Source/WebCore/css/StyleBuilderConverter.h
>+++ b/Source/WebCore/css/StyleBuilderConverter.h
>@@ -127,6 +127,7 @@ public:
> #if ENABLE(OVERFLOW_SCROLLING_TOUCH)
>     static bool convertOverflowScrolling(StyleResolver&, const CSSValue&);
> #endif
>+    static bool convertSmoothScrolling(StyleResolver&, const CSSValue&);
>     static FontFeatureSettings convertFontFeatureSettings(StyleResolver&, const CSSValue&);
>     static FontSelectionValue convertFontWeightFromValue(const CSSValue&);
>     static FontSelectionValue convertFontStretchFromValue(const CSSValue&);
>@@ -1404,6 +1405,11 @@ inline bool StyleBuilderConverter::convertOverflowScrolling(StyleResolver&, cons
> }
> #endif
> 
>+inline bool StyleBuilderConverter::convertSmoothScrolling(StyleResolver&, const CSSValue& value)
>+{
>+    return downcast<CSSPrimitiveValue>(value).valueID() == CSSValueSmooth;
>+}
>+
> inline SVGLengthValue StyleBuilderConverter::convertSVGLengthValue(StyleResolver&, const CSSValue& value)
> {
>     return SVGLengthValue::fromCSSPrimitiveValue(downcast<CSSPrimitiveValue>(value));
>diff --git a/Source/WebCore/css/parser/CSSParserContext.cpp b/Source/WebCore/css/parser/CSSParserContext.cpp
>index 7537188cb93..71f9aa62c4c 100644
>--- a/Source/WebCore/css/parser/CSSParserContext.cpp
>+++ b/Source/WebCore/css/parser/CSSParserContext.cpp
>@@ -75,6 +75,7 @@ CSSParserContext::CSSParserContext(const Document& document, const URL& sheetBas
>     attachmentEnabled = RuntimeEnabledFeatures::sharedFeatures().attachmentElementEnabled();
> #endif
>     deferredCSSParserEnabled = document.settings().deferredCSSParserEnabled();
>+    scrollBehaviorEnabled = document.settings().CSSOMViewSmoothScrollingEnabled();
>     useSystemAppearance = document.page() ? document.page()->useSystemAppearance() : false;
> }
> 
>@@ -99,6 +100,7 @@ bool operator==(const CSSParserContext& a, const CSSParserContext& b)
>         && a.attachmentEnabled == b.attachmentEnabled
> #endif
>         && a.deferredCSSParserEnabled == b.deferredCSSParserEnabled
>+        && a.scrollBehaviorEnabled == b.scrollBehaviorEnabled
>         && a.hasDocumentSecurityOrigin == b.hasDocumentSecurityOrigin
>         && a.useSystemAppearance == b.useSystemAppearance;
> }
>diff --git a/Source/WebCore/css/parser/CSSParserContext.h b/Source/WebCore/css/parser/CSSParserContext.h
>index a302b3878da..4a15b136a04 100644
>--- a/Source/WebCore/css/parser/CSSParserContext.h
>+++ b/Source/WebCore/css/parser/CSSParserContext.h
>@@ -61,6 +61,7 @@ public:
>     bool attachmentEnabled { false };
> #endif
>     bool deferredCSSParserEnabled { false };
>+    bool scrollBehaviorEnabled { false };
>     
>     // This is only needed to support getMatchedCSSRules.
>     bool hasDocumentSecurityOrigin { false };
>@@ -110,7 +111,8 @@ struct CSSParserContextHash {
> #if ENABLE(ATTACHMENT_ELEMENT)
>             & key.attachmentEnabled                         << 11
> #endif
>-            & key.mode                                      << 12; // Keep this last.
>+            & key.scrollBehaviorEnabled                     << 12
>+            & key.mode                                      << 13; // Keep this last.
>         hash ^= WTF::intHash(bits);
>         return hash;
>     }
>diff --git a/Source/WebCore/css/parser/CSSParserFastPaths.cpp b/Source/WebCore/css/parser/CSSParserFastPaths.cpp
>index b949cc8bd60..04ce31411d1 100644
>--- a/Source/WebCore/css/parser/CSSParserFastPaths.cpp
>+++ b/Source/WebCore/css/parser/CSSParserFastPaths.cpp
>@@ -634,10 +634,6 @@ bool CSSParserFastPaths::isValidKeywordPropertyAndValue(CSSPropertyID propertyId
>             || valueID == CSSValueSticky || valueID == CSSValueWebkitSticky;
>     case CSSPropertyResize: // none | both | horizontal | vertical | auto
>         return valueID == CSSValueNone || valueID == CSSValueBoth || valueID == CSSValueHorizontal || valueID == CSSValueVertical || valueID == CSSValueAuto;
>-    // FIXME-NEWPARSER: Investigate this property.
>-    // case CSSPropertyScrollBehavior: // auto | smooth
>-    //     ASSERT(RuntimeEnabledFeatures::cssomSmoothScrollEnabled());
>-    //   return valueID == CSSValueAuto || valueID == CSSValueSmooth;
>     case CSSPropertyShapeRendering:
>         return valueID == CSSValueAuto || valueID == CSSValueOptimizeSpeed || valueID == CSSValueCrispedges || valueID == CSSValueGeometricPrecision;
>     case CSSPropertyStrokeLinejoin:
>@@ -937,7 +933,6 @@ bool CSSParserFastPaths::isKeywordPropertyID(CSSPropertyID propertyId)
>     // case CSSPropertyFontKerning:
>     // case CSSPropertyHyphens:
>     // case CSSPropertyOverflowAnchor:
>-    // case CSSPropertyScrollBehavior:
>     // case CSSPropertyScrollSnapType:
>     // case CSSPropertyTextAlignLast:
>     // case CSSPropertyTextCombineUpright:
>diff --git a/Source/WebCore/css/parser/CSSPropertyParser.cpp b/Source/WebCore/css/parser/CSSPropertyParser.cpp
>index 902da151c03..25021d91816 100644
>--- a/Source/WebCore/css/parser/CSSPropertyParser.cpp
>+++ b/Source/WebCore/css/parser/CSSPropertyParser.cpp
>@@ -2323,6 +2323,14 @@ static RefPtr<CSSValueList> consumeScrollSnapType(CSSParserTokenRange& range)
> 
> #endif
> 
>+static RefPtr<CSSPrimitiveValue> consumeScrollBehavior(CSSParserTokenRange& range)
>+{
>+    auto valueID = range.peek().id();
>+    if (valueID != CSSValueAuto && valueID != CSSValueSmooth)
>+        return nullptr;
>+    return consumeIdent(range);
>+}
>+
> static RefPtr<CSSValue> consumeBorderRadiusCorner(CSSParserTokenRange& range, CSSParserMode cssParserMode)
> {
>     RefPtr<CSSPrimitiveValue> parsedValue1 = consumeLengthOrPercent(range, cssParserMode, ValueRangeNonNegative);
>@@ -3922,6 +3930,10 @@ RefPtr<CSSValue> CSSPropertyParser::parseSingleValue(CSSPropertyID property, CSS
>     case CSSPropertyScrollSnapType:
>         return consumeScrollSnapType(m_range);
> #endif
>+    case CSSPropertyScrollBehavior:
>+        if (!m_context.scrollBehaviorEnabled)
>+            return nullptr;
>+        return consumeScrollBehavior(m_range);
>     case CSSPropertyClip:
>         return consumeClip(m_range, m_context.mode);
> #if ENABLE(POINTER_EVENTS)
>diff --git a/Source/WebCore/dom/Element.cpp b/Source/WebCore/dom/Element.cpp
>index f07c5ec61d2..4bdd15c4bc3 100644
>--- a/Source/WebCore/dom/Element.cpp
>+++ b/Source/WebCore/dom/Element.cpp
>@@ -729,7 +729,6 @@ void Element::scrollIntoView(Optional<Variant<bool, ScrollIntoViewOptions>>&& ar
>     bool insideFixed;
>     LayoutRect absoluteBounds = renderer()->absoluteAnchorRect(&insideFixed);
> 
>-    // FIXME(webkit.org/b/188043): Support ScrollBehavior.
>     ScrollIntoViewOptions options;
>     if (arg) {
>         auto value = arg.value();
>@@ -739,9 +738,15 @@ void Element::scrollIntoView(Optional<Variant<bool, ScrollIntoViewOptions>>&& ar
>             options.blockPosition = ScrollLogicalPosition::End;
>     }
> 
>-    ScrollAlignment alignX = toScrollAlignment(options.inlinePosition, false);
>-    ScrollAlignment alignY = toScrollAlignment(options.blockPosition, true);
>-    renderer()->scrollRectToVisible(absoluteBounds, insideFixed, { SelectionRevealMode::Reveal, alignX, alignY, ShouldAllowCrossOriginScrolling::No });
>+    ScrollRectToVisibleOptions scrollRectToVisibleOptions {
>+        SelectionRevealMode::Reveal,
>+        toScrollAlignment(options.inlinePosition, false),
>+        toScrollAlignment(options.blockPosition, true),
>+        ShouldAllowCrossOriginScrolling::No,
>+    };
>+    if (options.behavior)
>+        scrollRectToVisibleOptions.behavior = options.behavior.value();
>+    renderer()->scrollRectToVisible(absoluteBounds, insideFixed, scrollRectToVisibleOptions);
> }
> 
> void Element::scrollIntoView(bool alignToTop) 
>@@ -800,7 +805,7 @@ void Element::scrollBy(const ScrollToOptions& options)
> 
> void Element::scrollBy(double x, double y)
> {
>-    scrollBy({ x, y });
>+    scrollBy(fromCoordinates(x, y));
> }
> 
> void Element::scrollTo(const ScrollToOptions& options, ScrollClamping clamping)
>@@ -836,13 +841,21 @@ void Element::scrollTo(const ScrollToOptions& options, ScrollClamping clamping)
>         adjustForAbsoluteZoom(renderer->scrollLeft(), *renderer),
>         adjustForAbsoluteZoom(renderer->scrollTop(), *renderer)
>     );
>-    renderer->setScrollLeft(clampToInteger(scrollToOptions.left.value() * renderer->style().effectiveZoom()), ScrollType::Programmatic, clamping);
>-    renderer->setScrollTop(clampToInteger(scrollToOptions.top.value() * renderer->style().effectiveZoom()), ScrollType::Programmatic, clamping);
>+    IntPoint scrollPosition(
>+        clampToInteger(scrollToOptions.left.value() * renderer->style().effectiveZoom()),
>+        clampToInteger(scrollToOptions.top.value() * renderer->style().effectiveZoom())
>+    );
>+    if (useSmoothScrolling(scrollToOptions.behavior.valueOr(ScrollBehavior::Auto), *this)) {
>+        renderer->scrollToPositionWithAnimation(scrollPosition, clamping);
>+        return;
>+    }
>+    renderer->setScrollLeft(scrollPosition.x(), ScrollType::Programmatic, clamping);
>+    renderer->setScrollTop(scrollPosition.y(), ScrollType::Programmatic, clamping);
> }
> 
> void Element::scrollTo(double x, double y)
> {
>-    scrollTo({ x, y });
>+    scrollTo(fromCoordinates(x, y));
> }
> 
> void Element::scrollByUnits(int units, ScrollGranularity granularity)
>diff --git a/Source/WebCore/page/DOMWindow.cpp b/Source/WebCore/page/DOMWindow.cpp
>index 29476b00b7e..41e0cd017eb 100644
>--- a/Source/WebCore/page/DOMWindow.cpp
>+++ b/Source/WebCore/page/DOMWindow.cpp
>@@ -1567,7 +1567,7 @@ double DOMWindow::devicePixelRatio() const
> 
> void DOMWindow::scrollBy(double x, double y) const
> {
>-    scrollBy({ x, y });
>+    scrollBy(fromCoordinates(x, y));
> }
> 
> void DOMWindow::scrollBy(const ScrollToOptions& options) const
>@@ -1589,10 +1589,10 @@ void DOMWindow::scrollBy(const ScrollToOptions& options) const
> 
> void DOMWindow::scrollTo(double x, double y, ScrollClamping clamping) const
> {
>-    scrollTo({ x, y }, clamping);
>+    scrollTo(fromCoordinates(x, y), clamping);
> }
> 
>-void DOMWindow::scrollTo(const ScrollToOptions& options, ScrollClamping) const
>+void DOMWindow::scrollTo(const ScrollToOptions& options, ScrollClamping clamping) const
> {
>     if (!isCurrentlyDisplayedInFrame())
>         return;
>@@ -1605,12 +1605,18 @@ void DOMWindow::scrollTo(const ScrollToOptions& options, ScrollClamping) const
>         view->contentsScrollPosition().x(), view->contentsScrollPosition().y()
>     );
> 
>-    if (!scrollToOptions.left.value() && !scrollToOptions.top.value() && view->contentsScrollPosition() == IntPoint(0, 0))
>+    if (!view->isScrollInProgress() && !scrollToOptions.left.value() && !scrollToOptions.top.value() && view->contentsScrollPosition() == IntPoint(0, 0))
>         return;
> 
>     document()->updateLayoutIgnorePendingStylesheets();
> 
>     IntPoint layoutPos(view->mapFromCSSToLayoutUnits(scrollToOptions.left.value()), view->mapFromCSSToLayoutUnits(scrollToOptions.top.value()));
>+    // FIXME: Should we use document()->scrollingElement()?
>+    // See https://github.com/w3c/csswg-drafts/issues/2977
>+    if (document()->documentElement() && useSmoothScrolling(scrollToOptions.behavior.valueOr(ScrollBehavior::Auto), *document()->documentElement())) {
>+        view->scrollToOffsetWithAnimation(layoutPos, clamping);
>+        return;
>+    }
>     view->setContentsScrollPosition(layoutPos);
> }
> 
>diff --git a/Source/WebCore/page/ScrollBehavior.cpp b/Source/WebCore/page/ScrollBehavior.cpp
>new file mode 100644
>index 00000000000..5328c9b83a8
>--- /dev/null
>+++ b/Source/WebCore/page/ScrollBehavior.cpp
>@@ -0,0 +1,48 @@
>+/*
>+ * Copyright (C) 2018 Igalia S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * along with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#include "config.h"
>+#include "ScrollBehavior.h"
>+
>+#include "Element.h"
>+#include "RenderElement.h"
>+#include "RenderStyle.h"
>+#include "Settings.h"
>+
>+namespace WebCore {
>+
>+bool useSmoothScrolling(ScrollBehavior behavior, Element& associatedElement)
>+{
>+    if (!associatedElement.document().settings().CSSOMViewSmoothScrollingEnabled() || !associatedElement.renderer())
>+        return false;
>+
>+    // https://drafts.csswg.org/cssom-view/#scrolling
>+    switch (behavior) {
>+    case ScrollBehavior::Auto:
>+        return associatedElement.renderer()->style().useSmoothScrolling();
>+    case ScrollBehavior::Instant:
>+        return false;
>+    case ScrollBehavior::Smooth:
>+        return true;
>+    }
>+    ASSERT_NOT_REACHED();
>+    return false;
>+}
>+
>+} // namespace WebCore
>diff --git a/Source/WebCore/page/ScrollBehavior.h b/Source/WebCore/page/ScrollBehavior.h
>new file mode 100644
>index 00000000000..f01497b0307
>--- /dev/null
>+++ b/Source/WebCore/page/ScrollBehavior.h
>@@ -0,0 +1,34 @@
>+/*
>+ * Copyright (C) 2018 Igalia S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * along with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#pragma once
>+
>+namespace WebCore {
>+
>+class Element;
>+
>+enum class ScrollBehavior : uint8_t {
>+    Auto = 0,
>+    Instant,
>+    Smooth
>+};
>+
>+bool useSmoothScrolling(ScrollBehavior, Element& associatedElement);
>+
>+} // namespace WebCore
>diff --git a/Source/WebCore/page/ScrollBehavior.idl b/Source/WebCore/page/ScrollBehavior.idl
>new file mode 100644
>index 00000000000..a865fbe665b
>--- /dev/null
>+++ b/Source/WebCore/page/ScrollBehavior.idl
>@@ -0,0 +1,20 @@
>+/*
>+ * Copyright (C) 2018 Igalia S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * along with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+enum ScrollBehavior { "auto", "instant", "smooth" };
>diff --git a/Source/WebCore/page/ScrollIntoViewOptions.h b/Source/WebCore/page/ScrollIntoViewOptions.h
>index 939cd73425a..f275f2fbd1a 100644
>--- a/Source/WebCore/page/ScrollIntoViewOptions.h
>+++ b/Source/WebCore/page/ScrollIntoViewOptions.h
>@@ -20,12 +20,11 @@
> #pragma once
> 
> #include "ScrollLogicalPosition.h"
>+#include "ScrollOptions.h"
> 
> namespace WebCore {
> 
>-class Element;
>-
>-struct ScrollIntoViewOptions {
>+struct ScrollIntoViewOptions : ScrollOptions {
>     Optional<ScrollLogicalPosition> blockPosition { ScrollLogicalPosition::Start };
>     Optional<ScrollLogicalPosition> inlinePosition { ScrollLogicalPosition::Nearest };
> };
>diff --git a/Source/WebCore/page/ScrollIntoViewOptions.idl b/Source/WebCore/page/ScrollIntoViewOptions.idl
>index cf9d1fd7678..1b24c686fc7 100644
>--- a/Source/WebCore/page/ScrollIntoViewOptions.idl
>+++ b/Source/WebCore/page/ScrollIntoViewOptions.idl
>@@ -17,8 +17,7 @@
>  * Boston, MA 02110-1301, USA.
>  */
> 
>-// FIXME(webkit.org/b/188043): Support ScrollBehavior.
>-dictionary ScrollIntoViewOptions {
>+dictionary ScrollIntoViewOptions : ScrollOptions {
>     [ImplementedAs=blockPosition] ScrollLogicalPosition block = "start";
>     [ImplementedAs=inlinePosition] ScrollLogicalPosition inline = "nearest";
> };
>diff --git a/Source/WebCore/page/ScrollOptions.h b/Source/WebCore/page/ScrollOptions.h
>new file mode 100644
>index 00000000000..e7f63b9ff1c
>--- /dev/null
>+++ b/Source/WebCore/page/ScrollOptions.h
>@@ -0,0 +1,30 @@
>+/*
>+ * Copyright (C) 2018 Igalia S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * along with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+#pragma once
>+
>+#include "ScrollBehavior.h"
>+
>+namespace WebCore {
>+
>+struct ScrollOptions {
>+    Optional<ScrollBehavior> behavior { ScrollBehavior::Auto };
>+};
>+
>+} // namespace WebCore
>diff --git a/Source/WebCore/page/ScrollOptions.idl b/Source/WebCore/page/ScrollOptions.idl
>new file mode 100644
>index 00000000000..140f5c70ed1
>--- /dev/null
>+++ b/Source/WebCore/page/ScrollOptions.idl
>@@ -0,0 +1,22 @@
>+/*
>+ * Copyright (C) 2018 Igalia S.L.
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Library General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Library General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Library General Public License
>+ * along with this library; see the file COPYING.LIB.  If not, write to
>+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
>+ * Boston, MA 02110-1301, USA.
>+ */
>+
>+dictionary ScrollOptions {
>+    ScrollBehavior behavior = "auto";
>+};
>diff --git a/Source/WebCore/page/ScrollToOptions.h b/Source/WebCore/page/ScrollToOptions.h
>index ce1cba1c7c0..65b6e571db9 100644
>--- a/Source/WebCore/page/ScrollToOptions.h
>+++ b/Source/WebCore/page/ScrollToOptions.h
>@@ -28,16 +28,25 @@
> 
> #pragma once
> 
>+#include "ScrollOptions.h"
> #include <cmath>
> #include <wtf/Optional.h>
> 
> namespace WebCore {
> 
>-struct ScrollToOptions {
>+struct ScrollToOptions : ScrollOptions {
>     Optional<double> left;
>     Optional<double> top;
> };
> 
>+inline ScrollToOptions fromCoordinates(double x, double y)
>+{
>+    ScrollToOptions options;
>+    options.left = x;
>+    options.top = y;
>+    return options;
>+};
>+
> inline double normalizeNonFiniteValueOrFallBackTo(Optional<double> value, double fallbackValue)
> {
>     // Normalize non-finite values (https://drafts.csswg.org/cssom-view/#normalize-non-finite-values).
>@@ -47,7 +56,7 @@ inline double normalizeNonFiniteValueOrFallBackTo(Optional<double> value, double
> // FIXME(https://webkit.org/b/88339): Consider using FloatPoint or DoublePoint for fallback and return values.
> inline ScrollToOptions normalizeNonFiniteCoordinatesOrFallBackTo(const ScrollToOptions& value, double x, double y)
> {
>-    ScrollToOptions options;
>+    ScrollToOptions options = value;
>     options.left = normalizeNonFiniteValueOrFallBackTo(value.left, x);
>     options.top = normalizeNonFiniteValueOrFallBackTo(value.top, y);
>     return options;
>diff --git a/Source/WebCore/page/ScrollToOptions.idl b/Source/WebCore/page/ScrollToOptions.idl
>index 510bc071a68..2b9b554122a 100644
>--- a/Source/WebCore/page/ScrollToOptions.idl
>+++ b/Source/WebCore/page/ScrollToOptions.idl
>@@ -26,8 +26,7 @@
>  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>  */
> 
>-// FIXME(webkit.org/b/188043): Support ScrollBehavior.
>-dictionary ScrollToOptions {
>+dictionary ScrollToOptions : ScrollOptions {
>     unrestricted double left;
>     unrestricted double top;
> };
>diff --git a/Source/WebCore/page/Settings.yaml b/Source/WebCore/page/Settings.yaml
>index cbc73a110fb..49ab6aeb080 100644
>--- a/Source/WebCore/page/Settings.yaml
>+++ b/Source/WebCore/page/Settings.yaml
>@@ -595,6 +595,9 @@ syntheticEditingCommandsEnabled:
> CSSOMViewScrollingAPIEnabled:
>   initial: false
> 
>+CSSOMViewSmoothScrollingEnabled:
>+  initial: false
>+
> inputEventsEnabled:
>   initial: true
> 
>diff --git a/Source/WebCore/platform/ScrollAnimation.h b/Source/WebCore/platform/ScrollAnimation.h
>index 2e5f63bcef2..501007e04d2 100644
>--- a/Source/WebCore/platform/ScrollAnimation.h
>+++ b/Source/WebCore/platform/ScrollAnimation.h
>@@ -32,15 +32,18 @@ namespace WebCore {
> 
> class FloatPoint;
> class ScrollableArea;
>+enum class ScrollClamping : uint8_t;
> 
> class ScrollAnimation {
> public:
>     virtual ~ScrollAnimation() { };
>     virtual bool scroll(ScrollbarOrientation, ScrollGranularity, float /* step */, float /* multiplier */) { return true; };
>+    virtual void scroll(const FloatPoint&, ScrollClamping) { };
>     virtual void stop() = 0;
>     virtual void updateVisibleLengths() { };
>     virtual void setCurrentPosition(const FloatPoint&) { };
>     virtual void serviceAnimation() { };
>+    virtual bool isScrollInProgress() const { return false; }
> 
> protected:
>     ScrollAnimation(ScrollableArea& scrollableArea)
>diff --git a/Source/WebCore/platform/ScrollAnimationKinetic.cpp b/Source/WebCore/platform/ScrollAnimationKinetic.cpp
>index ac9f2f0f37f..50fb6098409 100644
>--- a/Source/WebCore/platform/ScrollAnimationKinetic.cpp
>+++ b/Source/WebCore/platform/ScrollAnimationKinetic.cpp
>@@ -165,4 +165,9 @@ void ScrollAnimationKinetic::animationTimerFired()
>     m_notifyPositionChangedFunction(FloatPoint(m_position));
> }
> 
>+bool ScrollAnimationKinetic::isScrollInProgress() const
>+{
>+    return m_animationTimer.isActive();
>+}
>+
> } // namespace WebCore
>diff --git a/Source/WebCore/platform/ScrollAnimationKinetic.h b/Source/WebCore/platform/ScrollAnimationKinetic.h
>index cfd33ce5b49..291fa9c19a7 100644
>--- a/Source/WebCore/platform/ScrollAnimationKinetic.h
>+++ b/Source/WebCore/platform/ScrollAnimationKinetic.h
>@@ -66,6 +66,7 @@ public:
> private:
>     void stop() override;
>     void animationTimerFired();
>+    bool isScrollInProgress() const override;
> 
>     std::function<void(FloatPoint&&)> m_notifyPositionChangedFunction;
> 
>diff --git a/Source/WebCore/platform/ScrollAnimationSmooth.cpp b/Source/WebCore/platform/ScrollAnimationSmooth.cpp
>index d064e69379f..7cc1958a1c5 100644
>--- a/Source/WebCore/platform/ScrollAnimationSmooth.cpp
>+++ b/Source/WebCore/platform/ScrollAnimationSmooth.cpp
>@@ -28,8 +28,6 @@
> #include "config.h"
> #include "ScrollAnimationSmooth.h"
> 
>-#if ENABLE(SMOOTH_SCROLLING)
>-
> #include "FloatPoint.h"
> #include "ScrollableArea.h"
> 
>@@ -38,6 +36,7 @@ namespace WebCore {
> static const double frameRate = 60;
> static const Seconds tickTime = 1_s / frameRate;
> static const Seconds minimumTimerInterval { 1_ms };
>+static const double smoothFactorForProgrammaticScroll = 5;
> 
> ScrollAnimationSmooth::ScrollAnimationSmooth(ScrollableArea& scrollableArea, const FloatPoint& position, WTF::Function<void (FloatPoint&&)>&& notifyPositionChangedFunction)
>     : ScrollAnimation(scrollableArea)
>@@ -67,6 +66,19 @@ bool ScrollAnimationSmooth::scroll(ScrollbarOrientation orientation, ScrollGranu
>     return needToScroll;
> }
> 
>+void ScrollAnimationSmooth::scroll(const FloatPoint& position, ScrollClamping)
>+{
>+    // FIXME: Consider clamping?
>+    ScrollGranularity granularity = ScrollByPage;
>+    bool needToScroll = updatePerAxisData(m_horizontalData, granularity, position.x() - m_horizontalData.currentPosition, m_scrollableArea.minimumScrollPosition().x(), m_scrollableArea.maximumScrollPosition().x(), smoothFactorForProgrammaticScroll);
>+    needToScroll |=
>+        updatePerAxisData(m_verticalData, granularity, position.y() - m_verticalData.currentPosition, m_scrollableArea.minimumScrollPosition().y(), m_scrollableArea.maximumScrollPosition().y(), smoothFactorForProgrammaticScroll);
>+    if (needToScroll && !animationTimerActive()) {
>+        m_startTime = m_horizontalData.startTime;
>+        animationTimerFired();
>+    }
>+};
>+
> void ScrollAnimationSmooth::stop()
> {
>     m_animationTimer.stop();
>@@ -247,7 +259,7 @@ static inline void getAnimationParametersForGranularity(ScrollGranularity granul
>     }
> }
> 
>-bool ScrollAnimationSmooth::updatePerAxisData(PerAxisData& data, ScrollGranularity granularity, float delta, float minScrollPosition, float maxScrollPosition)
>+bool ScrollAnimationSmooth::updatePerAxisData(PerAxisData& data, ScrollGranularity granularity, float delta, float minScrollPosition, float maxScrollPosition, double smoothFactor)
> {
>     if (!data.startTime || !delta || (delta < 0) != (data.desiredPosition - data.currentPosition < 0)) {
>         data.desiredPosition = data.currentPosition;
>@@ -264,6 +276,12 @@ bool ScrollAnimationSmooth::updatePerAxisData(PerAxisData& data, ScrollGranulari
>     Curve coastTimeCurve;
>     getAnimationParametersForGranularity(granularity, animationTime, repeatMinimumSustainTime, attackTime, releaseTime, coastTimeCurve, maximumCoastTime);
> 
>+    animationTime *= smoothFactor;
>+    repeatMinimumSustainTime *= smoothFactor;
>+    attackTime *= smoothFactor;
>+    releaseTime *= smoothFactor;
>+    maximumCoastTime *= smoothFactor;
>+
>     data.desiredPosition = newPosition;
>     if (!data.startTime)
>         data.attackTime = attackTime;
>@@ -407,5 +425,3 @@ bool ScrollAnimationSmooth::animationTimerActive() const
> }
> 
> } // namespace WebCore
>-
>-#endif // ENABLE(SMOOTH_SCROLLING)
>diff --git a/Source/WebCore/platform/ScrollAnimationSmooth.h b/Source/WebCore/platform/ScrollAnimationSmooth.h
>index 02cc4ee2bd7..351889f3244 100644
>--- a/Source/WebCore/platform/ScrollAnimationSmooth.h
>+++ b/Source/WebCore/platform/ScrollAnimationSmooth.h
>@@ -27,14 +27,13 @@
> 
> #include "ScrollAnimation.h"
> 
>-#if ENABLE(SMOOTH_SCROLLING)
>-
> #include "Timer.h"
> 
> namespace WebCore {
> 
> class FloatPoint;
> class ScrollableArea;
>+enum class ScrollClamping : uint8_t;
> 
> class ScrollAnimationSmooth final: public ScrollAnimation {
> public:
>@@ -51,9 +50,11 @@ public:
> 
> private:
>     bool scroll(ScrollbarOrientation, ScrollGranularity, float step, float multiplier) override;
>+    void scroll(const FloatPoint&, ScrollClamping) override;
>     void stop() override;
>     void updateVisibleLengths() override;
>     void setCurrentPosition(const FloatPoint&) override;
>+    bool isScrollInProgress() const override { return animationTimerActive(); }
> 
>     struct PerAxisData {
>         PerAxisData() = delete;
>@@ -89,7 +90,7 @@ private:
>         int visibleLength { 0 };
>     };
> 
>-    bool updatePerAxisData(PerAxisData&, ScrollGranularity, float delta, float minScrollPosition, float maxScrollPosition);
>+    bool updatePerAxisData(PerAxisData&, ScrollGranularity, float delta, float minScrollPosition, float maxScrollPosition, double smoothFactor = 1);
>     bool animateScroll(PerAxisData&, MonotonicTime currentTime);
> 
>     void requestAnimationTimerFired();
>@@ -108,4 +109,3 @@ private:
> 
> } // namespace WebCore
> 
>-#endif // ENABLE(SMOOTH_SCROLLING)
>diff --git a/Source/WebCore/platform/ScrollAnimator.cpp b/Source/WebCore/platform/ScrollAnimator.cpp
>index d9154d9351a..e6c95f9062a 100644
>--- a/Source/WebCore/platform/ScrollAnimator.cpp
>+++ b/Source/WebCore/platform/ScrollAnimator.cpp
>@@ -35,6 +35,7 @@
> #include "FloatPoint.h"
> #include "LayoutSize.h"
> #include "PlatformWheelEvent.h"
>+#include "ScrollAnimationSmooth.h"
> #include "ScrollableArea.h"
> #include <algorithm>
> 
>@@ -52,11 +53,22 @@ ScrollAnimator::ScrollAnimator(ScrollableArea& scrollableArea)
> #if ENABLE(CSS_SCROLL_SNAP) || ENABLE(RUBBER_BANDING)
>     , m_scrollController(*this)
> #endif
>+    , m_animationProgrammaticScroll(std::make_unique<ScrollAnimationSmooth>(scrollableArea, m_currentPosition, [this](FloatPoint&& position) {
>+        FloatSize delta = position - m_currentPosition;
>+        m_currentPosition = WTFMove(position);
>+        notifyPositionChanged(delta);
>+    }))
> {
> }
> 
> ScrollAnimator::~ScrollAnimator() = default;
> 
>+bool ScrollAnimator::isScrollInProgress() const
>+{
>+    // FIXME (TODO): This should also take into account animations in derived classes.
>+    return m_animationProgrammaticScroll->isScrollInProgress();
>+}
>+
> bool ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity, float step, float multiplier)
> {
>     FloatPoint currentPosition = this->currentPosition();
>@@ -75,6 +87,13 @@ bool ScrollAnimator::scroll(ScrollbarOrientation orientation, ScrollGranularity,
>     return true;
> }
> 
>+void ScrollAnimator::scrollToOffset(const FloatPoint& offset, ScrollClamping clamping)
>+{
>+    m_animationProgrammaticScroll->setCurrentPosition(m_currentPosition);
>+    auto newPosition = ScrollableArea::scrollPositionFromOffset(offset, toFloatSize(m_scrollableArea.scrollOrigin()));
>+    m_animationProgrammaticScroll->scroll(newPosition, clamping);
>+}
>+
> void ScrollAnimator::scrollToOffsetWithoutAnimation(const FloatPoint& offset, ScrollClamping)
> {
>     FloatPoint newPositon = ScrollableArea::scrollPositionFromOffset(offset, toFloatSize(m_scrollableArea.scrollOrigin()));
>@@ -245,4 +264,33 @@ void ScrollAnimator::removeTestDeferralForReason(WheelEventTestTrigger::Scrollab
> }
> #endif
> 
>+void ScrollAnimator::cancelAnimations()
>+{
>+#if !USE(REQUEST_ANIMATION_FRAME_TIMER)
>+    m_animationProgrammaticScroll->stop();
>+#endif
>+}
>+
>+void ScrollAnimator::serviceScrollAnimations()
>+{
>+#if !USE(REQUEST_ANIMATION_FRAME_TIMER)
>+    m_animationProgrammaticScroll->serviceAnimation();
>+#endif
>+}
>+
>+void ScrollAnimator::willEndLiveResize()
>+{
>+    m_animationProgrammaticScroll->updateVisibleLengths();
>+}
>+
>+void ScrollAnimator::didAddVerticalScrollbar(Scrollbar*)
>+{
>+    m_animationProgrammaticScroll->updateVisibleLengths();
>+}
>+
>+void ScrollAnimator::didAddHorizontalScrollbar(Scrollbar*)
>+{
>+    m_animationProgrammaticScroll->updateVisibleLengths();
>+}
>+
> } // namespace WebCore
>diff --git a/Source/WebCore/platform/ScrollAnimator.h b/Source/WebCore/platform/ScrollAnimator.h
>index 6e2a884abb2..6914483d730 100644
>--- a/Source/WebCore/platform/ScrollAnimator.h
>+++ b/Source/WebCore/platform/ScrollAnimator.h
>@@ -46,6 +46,7 @@ namespace WebCore {
> 
> class FloatPoint;
> class PlatformTouchEvent;
>+class ScrollAnimation;
> class ScrollableArea;
> class Scrollbar;
> class WheelEventTestTrigger;
>@@ -68,6 +69,7 @@ public:
>     // The base class implementation always scrolls immediately, never animates.
>     virtual bool scroll(ScrollbarOrientation, ScrollGranularity, float step, float multiplier);
> 
>+    void scrollToOffset(const FloatPoint&, ScrollClamping = ScrollClamping::Clamped);
>     virtual void scrollToOffsetWithoutAnimation(const FloatPoint&, ScrollClamping = ScrollClamping::Clamped);
> 
>     ScrollableArea& scrollableArea() const { return m_scrollableArea; }
>@@ -85,8 +87,8 @@ public:
>     void setCurrentPosition(const FloatPoint&);
>     const FloatPoint& currentPosition() const { return m_currentPosition; }
> 
>-    virtual void cancelAnimations() { }
>-    virtual void serviceScrollAnimations() { }
>+    virtual void cancelAnimations();
>+    virtual void serviceScrollAnimations();
> 
>     virtual void contentAreaWillPaint() const { }
>     virtual void mouseEnteredContentArea() { }
>@@ -97,16 +99,16 @@ public:
>     virtual void mouseIsDownInScrollbar(Scrollbar*, bool) const { }
>     virtual void willStartLiveResize() { }
>     virtual void contentsResized() const { }
>-    virtual void willEndLiveResize() { }
>+    virtual void willEndLiveResize();
>     virtual void contentAreaDidShow() { }
>     virtual void contentAreaDidHide() { }
> 
>     virtual void lockOverlayScrollbarStateToHidden(bool) { }
>     virtual bool scrollbarsCanBeActive() const { return true; }
> 
>-    virtual void didAddVerticalScrollbar(Scrollbar*) { }
>+    virtual void didAddVerticalScrollbar(Scrollbar*);
>     virtual void willRemoveVerticalScrollbar(Scrollbar*) { }
>-    virtual void didAddHorizontalScrollbar(Scrollbar*) { }
>+    virtual void didAddHorizontalScrollbar(Scrollbar*);
>     virtual void willRemoveHorizontalScrollbar(Scrollbar*) { }
> 
>     virtual void invalidateScrollbarPartLayers(Scrollbar*) { }
>@@ -120,6 +122,7 @@ public:
> 
>     virtual bool isRubberBandInProgress() const { return false; }
>     virtual bool isScrollSnapInProgress() const { return false; }
>+    bool isScrollInProgress() const;
> 
>     void setWheelEventTestTrigger(RefPtr<WheelEventTestTrigger>&& testTrigger) { m_wheelEventTestTrigger = testTrigger; }
> #if (ENABLE(CSS_SCROLL_SNAP) || ENABLE(RUBBER_BANDING)) && PLATFORM(MAC)
>@@ -150,6 +153,8 @@ protected:
>     ScrollController m_scrollController;
> #endif
>     FloatPoint m_currentPosition;
>+
>+    std::unique_ptr<ScrollAnimation> m_animationProgrammaticScroll;
> };
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/platform/ScrollView.cpp b/Source/WebCore/platform/ScrollView.cpp
>index b126a9c2b70..b780f8c1d63 100644
>--- a/Source/WebCore/platform/ScrollView.cpp
>+++ b/Source/WebCore/platform/ScrollView.cpp
>@@ -475,9 +475,13 @@ void ScrollView::setScrollPosition(const ScrollPosition& scrollPosition)
> 
>     ScrollPosition newScrollPosition = !delegatesScrolling() ? adjustScrollPositionWithinRange(scrollPosition) : scrollPosition;
> 
>-    if ((!delegatesScrolling() || currentScrollType() == ScrollType::User) && newScrollPosition == this->scrollPosition())
>+    bool scrollInProgress = isScrollInProgress();
>+    if ((!delegatesScrolling() || currentScrollType() == ScrollType::User) && !scrollInProgress && newScrollPosition == this->scrollPosition())
>         return;
> 
>+    if (scrollInProgress)
>+        scrollAnimator().cancelAnimations();
>+
>     if (requestScrollPositionUpdate(newScrollPosition))
>         return;
> 
>diff --git a/Source/WebCore/platform/ScrollableArea.cpp b/Source/WebCore/platform/ScrollableArea.cpp
>index c8882ee2305..a925c175402 100644
>--- a/Source/WebCore/platform/ScrollableArea.cpp
>+++ b/Source/WebCore/platform/ScrollableArea.cpp
>@@ -101,6 +101,11 @@ float ScrollableArea::adjustScrollStepForFixedContent(float step, ScrollbarOrien
>     return step;
> }
> 
>+bool ScrollableArea::isScrollInProgress() const
>+{
>+    return m_scrollAnimator && scrollAnimator().isScrollInProgress();
>+}
>+
> bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granularity, float multiplier)
> {
>     ScrollbarOrientation orientation;
>@@ -139,6 +144,12 @@ bool ScrollableArea::scroll(ScrollDirection direction, ScrollGranularity granula
>     return scrollAnimator().scroll(orientation, granularity, step, multiplier);
> }
> 
>+void ScrollableArea::scrollToOffsetWithAnimation(const FloatPoint& offset, ScrollClamping clamping)
>+{
>+    LOG_WITH_STREAM(Scrolling, stream << "ScrollableArea " << this << " scrollToOffset " << offset);
>+    scrollAnimator().scrollToOffset(offset, clamping);
>+}
>+
> void ScrollableArea::scrollToOffsetWithoutAnimation(const FloatPoint& offset, ScrollClamping clamping)
> {
>     LOG_WITH_STREAM(Scrolling, stream << "ScrollableArea " << this << " scrollToOffsetWithoutAnimation " << offset);
>diff --git a/Source/WebCore/platform/ScrollableArea.h b/Source/WebCore/platform/ScrollableArea.h
>index d7438c15cd5..0014e327470 100644
>--- a/Source/WebCore/platform/ScrollableArea.h
>+++ b/Source/WebCore/platform/ScrollableArea.h
>@@ -62,7 +62,9 @@ inline int offsetForOrientation(ScrollOffset offset, ScrollbarOrientation orient
> 
> class ScrollableArea : public CanMakeWeakPtr<ScrollableArea> {
> public:
>+    WEBCORE_EXPORT bool isScrollInProgress() const;
>     WEBCORE_EXPORT bool scroll(ScrollDirection, ScrollGranularity, float multiplier = 1);
>+    WEBCORE_EXPORT void scrollToOffsetWithAnimation(const FloatPoint&, ScrollClamping = ScrollClamping::Clamped);
>     WEBCORE_EXPORT void scrollToOffsetWithoutAnimation(const FloatPoint&, ScrollClamping = ScrollClamping::Clamped);
>     void scrollToOffsetWithoutAnimation(ScrollbarOrientation, float offset);
> 
>diff --git a/Source/WebCore/platform/mac/ScrollAnimatorMac.mm b/Source/WebCore/platform/mac/ScrollAnimatorMac.mm
>index a83175122ec..ff07619c692 100644
>--- a/Source/WebCore/platform/mac/ScrollAnimatorMac.mm
>+++ b/Source/WebCore/platform/mac/ScrollAnimatorMac.mm
>@@ -1151,6 +1151,7 @@ void ScrollAnimatorMac::notifyContentAreaScrolled(const FloatSize& delta)
> 
> void ScrollAnimatorMac::cancelAnimations()
> {
>+    ScrollAnimator::cancelAnimations();
>     m_haveScrolledSincePageLoad = false;
> 
>     if (scrollbarPaintTimerIsActive())
>diff --git a/Source/WebCore/rendering/RenderBox.cpp b/Source/WebCore/rendering/RenderBox.cpp
>index c7ed22358b0..308e5eed3e2 100644
>--- a/Source/WebCore/rendering/RenderBox.cpp
>+++ b/Source/WebCore/rendering/RenderBox.cpp
>@@ -591,6 +591,14 @@ void RenderBox::setScrollTop(int newTop, ScrollType scrollType, ScrollClamping c
>     layer()->scrollToYPosition(newTop, scrollType, clamping);
> }
> 
>+void RenderBox::scrollToPositionWithAnimation(ScrollPosition scrollPosition, ScrollClamping clamping)
>+{
>+    if (!hasOverflowClip() || !layer())
>+        return;
>+    setupWheelEventTestTrigger(*layer());
>+    layer()->scrollToOffsetWithAnimation(scrollPosition, clamping);
>+}
>+
> void RenderBox::absoluteRects(Vector<IntRect>& rects, const LayoutPoint& accumulatedOffset) const
> {
>     rects.append(snappedIntRect(accumulatedOffset, size()));
>diff --git a/Source/WebCore/rendering/RenderBox.h b/Source/WebCore/rendering/RenderBox.h
>index b2afd00acf5..ca1b0d36605 100644
>--- a/Source/WebCore/rendering/RenderBox.h
>+++ b/Source/WebCore/rendering/RenderBox.h
>@@ -249,6 +249,7 @@ public:
>     virtual int scrollHeight() const;
>     virtual void setScrollLeft(int, ScrollType, ScrollClamping = ScrollClamping::Clamped);
>     virtual void setScrollTop(int, ScrollType, ScrollClamping = ScrollClamping::Clamped);
>+    void scrollToPositionWithAnimation(ScrollPosition, ScrollClamping = ScrollClamping::Clamped);
> 
>     LayoutUnit marginTop() const override { return m_marginBox.top(); }
>     LayoutUnit marginBottom() const override { return m_marginBox.bottom(); }
>diff --git a/Source/WebCore/rendering/RenderLayer.cpp b/Source/WebCore/rendering/RenderLayer.cpp
>index ca7290a02d3..2fb2a8f6e5e 100644
>--- a/Source/WebCore/rendering/RenderLayer.cpp
>+++ b/Source/WebCore/rendering/RenderLayer.cpp
>@@ -114,6 +114,7 @@
> #include "ScaleTransformOperation.h"
> #include "ScriptDisallowedScope.h"
> #include "ScrollAnimator.h"
>+#include "ScrollBehavior.h"
> #include "Scrollbar.h"
> #include "ScrollbarTheme.h"
> #include "ScrollingCoordinator.h"
>@@ -2448,12 +2449,25 @@ void RenderLayer::scrollToOffset(const ScrollOffset& scrollOffset, ScrollType sc
>         handled = scrollingCoordinator->requestScrollPositionUpdate(*this, scrollPositionFromOffset(clampedScrollOffset));
> #endif
> 
>-    if (!handled)
>+    bool scrollInProgress = isScrollInProgress();
>+    if (scrollInProgress)
>+        scrollAnimator().cancelAnimations();
>+    if (scrollInProgress || !handled)
>         scrollToOffsetWithoutAnimation(clampedScrollOffset, clamping);
> 
>     setCurrentScrollType(previousScrollType);
> }
> 
>+void RenderLayer::scrollToOffsetWithAnimation(const ScrollOffset& scrollOffset, ScrollClamping clamping)
>+{
>+    ScrollOffset newScrollOffset = clamping == ScrollClamping::Clamped ? clampScrollOffset(scrollOffset) : scrollOffset;
>+    bool scrollInProgress = isScrollInProgress();
>+    if (scrollInProgress)
>+        scrollAnimator().cancelAnimations();
>+    if (scrollInProgress || newScrollOffset != this->scrollOffset())
>+        ScrollableArea::scrollToOffsetWithAnimation(newScrollOffset, clamping);
>+}
>+
> void RenderLayer::scrollTo(const ScrollPosition& position)
> {
>     RenderBox* box = renderBox();
>@@ -2603,6 +2617,7 @@ bool RenderLayer::allowsCurrentScroll() const
> 
> void RenderLayer::scrollRectToVisible(const LayoutRect& absoluteRect, bool insideFixed, const ScrollRectToVisibleOptions& options)
> {
>+    // FIXME (https://webkit.org/b/189907): Make this work with nested scrollable boxes when a smooth scrolling must be performed.
>     LOG_WITH_STREAM(Scrolling, stream << "Layer " << this << " scrollRectToVisible " << absoluteRect);
> 
>     RenderLayer* parentLayer = nullptr;
>@@ -2625,9 +2640,12 @@ void RenderLayer::scrollRectToVisible(const LayoutRect& absoluteRect, bool insid
>         LayoutRect revealRect = getRectToExpose(layerBounds, localExposeRect, insideFixed, options.alignX, options.alignY);
> 
>         ScrollOffset clampedScrollOffset = clampScrollOffset(scrollOffset() + toIntSize(roundedIntRect(revealRect).location()));
>-        if (clampedScrollOffset != scrollOffset()) {
>+        if (isScrollInProgress() || clampedScrollOffset != scrollOffset()) {
>             ScrollOffset oldScrollOffset = scrollOffset();
>-            scrollToOffset(clampedScrollOffset);
>+            if (box->element() && useSmoothScrolling(options.behavior, *box->element()))
>+                scrollToOffsetWithAnimation(clampedScrollOffset);
>+            else
>+                scrollToOffset(clampedScrollOffset);
>             IntSize scrollOffsetDifference = scrollOffset() - oldScrollOffset;
>             localExposeRect.move(-scrollOffsetDifference);
>             newRect = LayoutRect(box->localToAbsoluteQuad(FloatQuad(FloatRect(localExposeRect)), UseTransforms).boundingBox());
>@@ -2651,7 +2669,12 @@ void RenderLayer::scrollRectToVisible(const LayoutRect& absoluteRect, bool insid
>                 IntPoint scrollOffset(roundedIntPoint(exposeRect.location()));
>                 // Adjust offsets if they're outside of the allowable range.
>                 scrollOffset = scrollOffset.constrainedBetween(IntPoint(), IntPoint(frameView.contentsSize()));
>-                frameView.setScrollPosition(scrollOffset);
>+                // FIXME: Should we use contentDocument()->scrollingElement()?
>+                // See https://github.com/w3c/csswg-drafts/issues/2977
>+                if (ownerElement->contentDocument() && ownerElement->contentDocument()->documentElement() && useSmoothScrolling(options.behavior, *ownerElement->contentDocument()->documentElement()))
>+                    frameView.scrollToOffsetWithAnimation(scrollOffset);
>+                else
>+                    frameView.setScrollPosition(scrollOffset);
> 
>                 if (options.shouldAllowCrossOriginScrolling == ShouldAllowCrossOriginScrolling::Yes || frameView.safeToPropagateScrollToParent()) {
>                     parentLayer = ownerElement->renderer()->enclosingLayer();
>@@ -2685,7 +2708,13 @@ void RenderLayer::scrollRectToVisible(const LayoutRect& absoluteRect, bool insid
> 
>             LayoutRect revealRect = getRectToExpose(viewRect, targetRect, insideFixed, options.alignX, options.alignY);
>             ScrollOffset clampedScrollPosition = roundedIntPoint(revealRect.location()).constrainedBetween(minScrollPosition, maxScrollPosition);
>-            frameView.setScrollPosition(clampedScrollPosition);
>+            IntPoint scrollOffset(clampedScrollPosition);
>+            // FIXME: Should we use document()->scrollingElement()?
>+            // See https://github.com/w3c/csswg-drafts/issues/2977
>+            if (renderer().document().documentElement() && useSmoothScrolling(options.behavior, *renderer().document().documentElement()))
>+                frameView.scrollToOffsetWithAnimation(scrollOffset);
>+            else
>+                frameView.setScrollPosition(scrollOffset);
> 
>             // This is the outermost view of a web page, so after scrolling this view we
>             // scroll its container by calling Page::scrollRectIntoView.
>diff --git a/Source/WebCore/rendering/RenderLayer.h b/Source/WebCore/rendering/RenderLayer.h
>index 8cc87588a0c..f8dbea7bb13 100644
>--- a/Source/WebCore/rendering/RenderLayer.h
>+++ b/Source/WebCore/rendering/RenderLayer.h
>@@ -50,6 +50,7 @@
> #include "PaintInfo.h"
> #include "RenderBox.h"
> #include "RenderPtr.h"
>+#include "ScrollBehavior.h"
> #include "ScrollableArea.h"
> #include <memory>
> #include <wtf/WeakPtr.h>
>@@ -133,6 +134,7 @@ struct ScrollRectToVisibleOptions {
>     const ScrollAlignment& alignX { ScrollAlignment::alignCenterIfNeeded };
>     const ScrollAlignment& alignY { ScrollAlignment::alignCenterIfNeeded };
>     ShouldAllowCrossOriginScrolling shouldAllowCrossOriginScrolling { ShouldAllowCrossOriginScrolling::No };
>+    ScrollBehavior behavior { ScrollBehavior::Auto };
> };
> 
> class RenderLayer final : public ScrollableArea {
>@@ -431,6 +433,7 @@ public:
>     void scrollByRecursively(const IntSize& delta, ScrollableArea** scrolledArea = nullptr);
> 
>     WEBCORE_EXPORT void scrollToOffset(const ScrollOffset&, ScrollType = ScrollType::Programmatic, ScrollClamping = ScrollClamping::Clamped);
>+    WEBCORE_EXPORT void scrollToOffsetWithAnimation(const ScrollOffset&, ScrollClamping = ScrollClamping::Clamped);
> 
>     void scrollToXPosition(int x, ScrollType, ScrollClamping = ScrollClamping::Clamped);
>     void scrollToYPosition(int y, ScrollType, ScrollClamping = ScrollClamping::Clamped);
>diff --git a/Source/WebCore/rendering/style/RenderStyle.h b/Source/WebCore/rendering/style/RenderStyle.h
>index c0d837d5cf5..94ffad63bb4 100644
>--- a/Source/WebCore/rendering/style/RenderStyle.h
>+++ b/Source/WebCore/rendering/style/RenderStyle.h
>@@ -738,6 +738,8 @@ public:
>     bool useTouchOverflowScrolling() const { return m_rareInheritedData->useTouchOverflowScrolling; }
> #endif
> 
>+    bool useSmoothScrolling() const { return m_rareNonInheritedData->useSmoothScrolling; }
>+
> #if ENABLE(TEXT_AUTOSIZING)
>     TextSizeAdjustment textSizeAdjust() const { return m_rareInheritedData->textSizeAdjust; }
>     AutosizeStatus autosizeStatus() const;
>@@ -1248,6 +1250,8 @@ public:
>     void setUseTouchOverflowScrolling(bool v) { SET_VAR(m_rareInheritedData, useTouchOverflowScrolling, v); }
> #endif
> 
>+    void setUseSmoothScrolling(bool v) { SET_VAR(m_rareNonInheritedData, useSmoothScrolling, v); }
>+
> #if ENABLE(TEXT_AUTOSIZING)
>     void setTextSizeAdjust(TextSizeAdjustment adjustment) { SET_VAR(m_rareInheritedData, textSizeAdjust, adjustment); }
>     void setAutosizeStatus(AutosizeStatus);
>@@ -1685,6 +1689,8 @@ public:
>     static bool initialUseTouchOverflowScrolling() { return false; }
> #endif
> 
>+    static bool initialUseSmoothScrolling() { return false; }
>+
>     static const FilterOperations& initialFilter() { static NeverDestroyed<FilterOperations> ops; return ops; }
>     static const FilterOperations& initialAppleColorFilter() { static NeverDestroyed<FilterOperations> ops; return ops; }
> 
>diff --git a/Source/WebCore/rendering/style/StyleRareNonInheritedData.cpp b/Source/WebCore/rendering/style/StyleRareNonInheritedData.cpp
>index 6fbb2b7b0c3..f951078e97a 100644
>--- a/Source/WebCore/rendering/style/StyleRareNonInheritedData.cpp
>+++ b/Source/WebCore/rendering/style/StyleRareNonInheritedData.cpp
>@@ -80,6 +80,7 @@ StyleRareNonInheritedData::StyleRareNonInheritedData()
> #if ENABLE(POINTER_EVENTS)
>     , touchActions(static_cast<unsigned>(RenderStyle::initialTouchActions()))
> #endif
>+    , useSmoothScrolling(static_cast<unsigned>(RenderStyle::initialUseSmoothScrolling()))
>     , pageSizeType(PAGE_SIZE_AUTO)
>     , transformStyle3D(static_cast<unsigned>(RenderStyle::initialTransformStyle3D()))
>     , backfaceVisibility(static_cast<unsigned>(RenderStyle::initialBackfaceVisibility()))
>@@ -174,6 +175,7 @@ inline StyleRareNonInheritedData::StyleRareNonInheritedData(const StyleRareNonIn
> #if ENABLE(POINTER_EVENTS)
>     , touchActions(o.touchActions)
> #endif
>+    , useSmoothScrolling(o.useSmoothScrolling)
>     , pageSizeType(o.pageSizeType)
>     , transformStyle3D(o.transformStyle3D)
>     , backfaceVisibility(o.backfaceVisibility)
>@@ -286,6 +288,7 @@ bool StyleRareNonInheritedData::operator==(const StyleRareNonInheritedData& o) c
> #if ENABLE(POINTER_EVENTS)
>         && touchActions == o.touchActions
> #endif
>+        && useSmoothScrolling == o.useSmoothScrolling
> #if ENABLE(CSS_COMPOSITING)
>         && effectiveBlendMode == o.effectiveBlendMode
>         && isolation == o.isolation
>diff --git a/Source/WebCore/rendering/style/StyleRareNonInheritedData.h b/Source/WebCore/rendering/style/StyleRareNonInheritedData.h
>index 19c591b2d12..58f1c6ccf66 100644
>--- a/Source/WebCore/rendering/style/StyleRareNonInheritedData.h
>+++ b/Source/WebCore/rendering/style/StyleRareNonInheritedData.h
>@@ -175,6 +175,8 @@ public:
>     unsigned touchActions : 6; // TouchAction
> #endif
> 
>+    unsigned useSmoothScrolling : 1; // ScrollBehavior
>+
>     unsigned pageSizeType : 2; // PageSizeType
>     unsigned transformStyle3D : 1; // TransformStyle3D
>     unsigned backfaceVisibility : 1; // BackfaceVisibility
>diff --git a/Source/WebCore/testing/Internals.cpp b/Source/WebCore/testing/Internals.cpp
>index acde12f8de4..173bfdd571e 100644
>--- a/Source/WebCore/testing/Internals.cpp
>+++ b/Source/WebCore/testing/Internals.cpp
>@@ -1711,7 +1711,7 @@ ExceptionOr<void> Internals::unconstrainedScrollTo(Element& element, double x, d
>     if (!document || !document->view())
>         return Exception { InvalidAccessError };
> 
>-    element.scrollTo({ x, y }, ScrollClamping::Unclamped);
>+    element.scrollTo(fromCoordinates(x, y), ScrollClamping::Unclamped);
>     return { };
> }
> 
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index 4e8cb65c981..51a45365973 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,14 @@
>+2018-11-06  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Add CSSOM smooth scrolling as an experimental feature.
>+
>+        * Shared/WebPreferences.yaml:
>+
> 2019-06-24  Brady Eidson  <beidson@apple.com>
> 
>         Null deref in WebFrameLoaderClient::dispatchDidReceiveServerRedirectForProvisionalLoad.
>diff --git a/Source/WebKit/Shared/WebPreferences.yaml b/Source/WebKit/Shared/WebPreferences.yaml
>index 4174681ace7..1abdc6d0e4b 100644
>--- a/Source/WebKit/Shared/WebPreferences.yaml
>+++ b/Source/WebKit/Shared/WebPreferences.yaml
>@@ -1221,7 +1221,6 @@ ShouldDecidePolicyBeforeLoadingQuickLookPreview:
> #   DEFAULT_EXPERIMENTAL_FEATURES_ENABLED (for features that are ready for
> #   wider testing).
> 
>-
> SpringTimingFunctionEnabled:
>   type: bool
>   defaultValue: DEFAULT_EXPERIMENTAL_FEATURES_ENABLED
>@@ -1282,6 +1281,13 @@ BlockingOfSmallPluginsEnabled:
>   humanReadableDescription: "Stop plugins smaller than a certain threshold from loading."
>   category: internal
> 
>+CSSOMViewSmoothScrollingEnabled:
>+  type: bool
>+  defaultValue: false
>+  humanReadableName: "CSSOM View Smooth Scrolling"
>+  humanReadableDescription: "Enable DOM API and CSS property for 'smooth' scroll behavior"
>+  category: experimental
>+
> WebAnimationsEnabled:
>   type: bool
>   defaultValue: DEFAULT_EXPERIMENTAL_FEATURES_ENABLED
>diff --git a/Source/WebKitLegacy/mac/ChangeLog b/Source/WebKitLegacy/mac/ChangeLog
>index fe432d06460..923bd484bc4 100644
>--- a/Source/WebKitLegacy/mac/ChangeLog
>+++ b/Source/WebKitLegacy/mac/ChangeLog
>@@ -1,3 +1,20 @@
>+2018-11-07  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * WebView/WebPreferenceKeysPrivate.h: Handle CSSOMViewSmoothScrolling by.
>+        * WebView/WebPreferencesPrivate.h: Ditto.
>+        * WebView/WebView.mm:
>+        (-[WebView _preferencesChanged:]): Ditto.
>+
>+        * WebView/WebPreferences.mm:
>+        (+[WebPreferences initialize]): Disable CSSOMViewSmoothScrolling by default.
>+        (-[WebPreferences CSSOMViewSmoothScrollingEnabled]): Getter.
>+        (-[WebPreferences setCSSOMViewSmoothScrollingEnabled:]): Setter.
>+
> 2019-06-16  Darin Adler  <darin@apple.com>
> 
>         Rename AtomicString to AtomString
>diff --git a/Source/WebKitLegacy/mac/WebView/WebPreferenceKeysPrivate.h b/Source/WebKitLegacy/mac/WebView/WebPreferenceKeysPrivate.h
>index 86addf6a11b..2afe65ea7df 100644
>--- a/Source/WebKitLegacy/mac/WebView/WebPreferenceKeysPrivate.h
>+++ b/Source/WebKitLegacy/mac/WebView/WebPreferenceKeysPrivate.h
>@@ -185,6 +185,7 @@
> #define WebKitDirectoryUploadEnabledPreferenceKey @"WebKitDirectoryUploadEnabled"
> #define WebKitVisualViewportAPIEnabledPreferenceKey @"WebKitVisualViewportAPIEnabled"
> #define WebKitCSSOMViewScrollingAPIEnabledPreferenceKey @"WebKitCSSOMViewScrollingAPIEnabled"
>+#define WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey @"WebKitCSSOMViewSmoothScrollingEnabled"
> #define WebKitModernMediaControlsEnabledPreferenceKey @"WebKitModernMediaControlsEnabled"
> #define WebKitSubtleCryptoEnabledPreferenceKey @"WebKitSubtleCryptoEnabled"
> #define WebKitMediaDevicesEnabledPreferenceKey @"WebKitMediaDevicesEnabled"
>diff --git a/Source/WebKitLegacy/mac/WebView/WebPreferences.mm b/Source/WebKitLegacy/mac/WebView/WebPreferences.mm
>index ec913276914..93422778069 100644
>--- a/Source/WebKitLegacy/mac/WebView/WebPreferences.mm
>+++ b/Source/WebKitLegacy/mac/WebView/WebPreferences.mm
>@@ -652,6 +652,7 @@ public:
> #endif
> 
>         [NSNumber numberWithBool:NO], WebKitCSSOMViewScrollingAPIEnabledPreferenceKey,
>+        [NSNumber numberWithBool:NO], WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey,
>         [NSNumber numberWithBool:YES], WebKitNeedsStorageAccessFromFileURLsQuirkKey,
>         [NSNumber numberWithBool:NO], WebKitAllowCrossOriginSubresourcesToAskForCredentialsKey,
> #if ENABLE(MEDIA_STREAM)
>@@ -3137,6 +3138,16 @@ static NSString *classIBCreatorID = nil;
>     [self _setBoolValue:flag forKey:WebKitCSSOMViewScrollingAPIEnabledPreferenceKey];
> }
> 
>+- (BOOL)CSSOMViewSmoothScrollingEnabled
>+{
>+    return [self _boolValueForKey:WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey];
>+}
>+
>+- (void)setCSSOMViewSmoothScrollingEnabled:(BOOL)flag
>+{
>+    [self _setBoolValue:flag forKey:WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey];
>+}
>+
> - (BOOL)webAnimationsEnabled
> {
>     return [self _boolValueForKey:WebKitWebAnimationsEnabledPreferenceKey];
>diff --git a/Source/WebKitLegacy/mac/WebView/WebPreferencesPrivate.h b/Source/WebKitLegacy/mac/WebView/WebPreferencesPrivate.h
>index a8b9ac72062..830e41e11bc 100644
>--- a/Source/WebKitLegacy/mac/WebView/WebPreferencesPrivate.h
>+++ b/Source/WebKitLegacy/mac/WebView/WebPreferencesPrivate.h
>@@ -614,6 +614,7 @@ extern NSString *WebPreferencesCacheModelChangedInternalNotification WEBKIT_DEPR
> 
> @property (nonatomic) BOOL visualViewportAPIEnabled;
> @property (nonatomic) BOOL CSSOMViewScrollingAPIEnabled;
>+@property (nonatomic) BOOL CSSOMViewSmoothScrollingEnabled;
> @property (nonatomic) BOOL largeImageAsyncDecodingEnabled;
> @property (nonatomic) BOOL animatedImageAsyncDecodingEnabled;
> @property (nonatomic) BOOL javaScriptMarkupEnabled;
>diff --git a/Source/WebKitLegacy/mac/WebView/WebView.mm b/Source/WebKitLegacy/mac/WebView/WebView.mm
>index 6e13500c5d5..699e3f6c93f 100644
>--- a/Source/WebKitLegacy/mac/WebView/WebView.mm
>+++ b/Source/WebKitLegacy/mac/WebView/WebView.mm
>@@ -2983,6 +2983,7 @@ static bool needsSelfRetainWhileLoadingQuirk()
>     settings.setVisualViewportAPIEnabled([preferences visualViewportAPIEnabled]);
>     settings.setSyntheticEditingCommandsEnabled([preferences syntheticEditingCommandsEnabled]);
>     settings.setCSSOMViewScrollingAPIEnabled([preferences CSSOMViewScrollingAPIEnabled]);
>+    settings.setCSSOMViewSmoothScrollingEnabled([preferences CSSOMViewSmoothScrollingEnabled]);
>     settings.setMediaContentTypesRequiringHardwareSupport([preferences mediaContentTypesRequiringHardwareSupport]);
> 
>     switch ([preferences storageBlockingPolicy]) {
>diff --git a/Source/WebKitLegacy/win/ChangeLog b/Source/WebKitLegacy/win/ChangeLog
>index 601d76234ce..a4e9b5331bb 100644
>--- a/Source/WebKitLegacy/win/ChangeLog
>+++ b/Source/WebKitLegacy/win/ChangeLog
>@@ -1,3 +1,20 @@
>+2018-11-07  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * Interfaces/IWebPreferencesPrivate.idl: Handle smooth scrolling option.
>+        * WebPreferenceKeysPrivate.h: Ditto.
>+        * WebPreferences.cpp: Ditto.
>+        (WebPreferences::initializeDefaultSettings):
>+        (WebPreferences::CSSOMViewSmoothScrollingEnabled):
>+        (WebPreferences::setCSSOMViewSmoothScrollingEnabled):
>+        * WebPreferences.h: Ditto.
>+        * WebView.cpp: Ditto.
>+        (WebView::notifyPreferencesChanged):
>+
> 2019-06-16  Darin Adler  <darin@apple.com>
> 
>         Rename AtomicString to AtomString
>diff --git a/Source/WebKitLegacy/win/Interfaces/IWebPreferencesPrivate.idl b/Source/WebKitLegacy/win/Interfaces/IWebPreferencesPrivate.idl
>index cb8dda4aefb..e1adfdcd582 100644
>--- a/Source/WebKitLegacy/win/Interfaces/IWebPreferencesPrivate.idl
>+++ b/Source/WebKitLegacy/win/Interfaces/IWebPreferencesPrivate.idl
>@@ -223,6 +223,8 @@ interface IWebPreferencesPrivate6 : IWebPreferencesPrivate5
>     HRESULT setVisualViewportAPIEnabled([in] BOOL enabled);
>     HRESULT CSSOMViewScrollingAPIEnabled([out, retval] BOOL*);
>     HRESULT setCSSOMViewScrollingAPIEnabled([in] BOOL enabled);
>+    HRESULT CSSOMViewSmoothScrollingEnabled([out, retval] BOOL*);
>+    HRESULT setCSSOMViewSmoothScrollingEnabled([in] BOOL enabled);
>     HRESULT fetchAPIKeepAliveEnabled([out, retval] BOOL* enabled);
>     HRESULT setFetchAPIKeepAliveEnabled([in] BOOL enabled);
>     HRESULT spatialNavigationEnabled([out, retval] BOOL *enabled);
>diff --git a/Source/WebKitLegacy/win/WebPreferenceKeysPrivate.h b/Source/WebKitLegacy/win/WebPreferenceKeysPrivate.h
>index ba662703ab8..6d80b2c2f89 100644
>--- a/Source/WebKitLegacy/win/WebPreferenceKeysPrivate.h
>+++ b/Source/WebKitLegacy/win/WebPreferenceKeysPrivate.h
>@@ -205,6 +205,7 @@
> #define WebKitServerTimingEnabledPreferenceKey "WebKitServerTimingEnabled"
> 
> #define WebKitCSSOMViewScrollingAPIEnabledPreferenceKey "WebKitCSSOMViewScrollingAPIEnabled"
>+#define WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey "WebKitCSSOMViewSmoothScrollingEnabled"
> 
> #define WebKitResizeObserverEnabledPreferenceKey "WebKitResizeObserverEnabled"
> 
>diff --git a/Source/WebKitLegacy/win/WebPreferences.cpp b/Source/WebKitLegacy/win/WebPreferences.cpp
>index 13948686bcf..2a5d71de92e 100644
>--- a/Source/WebKitLegacy/win/WebPreferences.cpp
>+++ b/Source/WebKitLegacy/win/WebPreferences.cpp
>@@ -333,6 +333,8 @@ void WebPreferences::initializeDefaultSettings()
> 
>     CFDictionaryAddValue(defaults, CFSTR(WebKitCoreMathMLEnabledPreferenceKey), kCFBooleanFalse);
> 
>+    CFDictionaryAddValue(defaults, CFSTR(WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey), kCFBooleanFalse);
>+
>     defaultSettings = defaults;
> }
> 
>@@ -2216,6 +2218,20 @@ HRESULT WebPreferences::setCoreMathMLEnabled(BOOL enabled)
>     setBoolValue(WebKitCoreMathMLEnabledPreferenceKey, enabled);
>     return S_OK;
> }
>+    
>+HRESULT WebPreferences::CSSOMViewSmoothScrollingEnabled(_Out_ BOOL* enabled)
>+{
>+    if (!enabled)
>+        return E_POINTER;
>+    *enabled = boolValueForKey(WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey);
>+    return S_OK;
>+}
>+
>+HRESULT WebPreferences::setCSSOMViewSmoothScrollingEnabled(BOOL enabled)
>+{
>+    setBoolValue(WebKitCSSOMViewSmoothScrollingEnabledPreferenceKey, enabled);
>+    return S_OK;
>+}
> 
> HRESULT WebPreferences::setApplicationId(BSTR applicationId)
> {
>diff --git a/Source/WebKitLegacy/win/WebPreferences.h b/Source/WebKitLegacy/win/WebPreferences.h
>index 5ee6427b353..71a73272cce 100644
>--- a/Source/WebKitLegacy/win/WebPreferences.h
>+++ b/Source/WebKitLegacy/win/WebPreferences.h
>@@ -271,6 +271,8 @@ public:
>     virtual HRESULT STDMETHODCALLTYPE setVisualViewportAPIEnabled(BOOL);
>     virtual HRESULT STDMETHODCALLTYPE CSSOMViewScrollingAPIEnabled(_Out_ BOOL*);
>     virtual HRESULT STDMETHODCALLTYPE setCSSOMViewScrollingAPIEnabled(BOOL);
>+    virtual HRESULT STDMETHODCALLTYPE CSSOMViewSmoothScrollingEnabled(_Out_ BOOL*);
>+    virtual HRESULT STDMETHODCALLTYPE setCSSOMViewSmoothScrollingEnabled(BOOL);
>     virtual HRESULT STDMETHODCALLTYPE fetchAPIKeepAliveEnabled(_Out_ BOOL*);
>     virtual HRESULT STDMETHODCALLTYPE setFetchAPIKeepAliveEnabled(BOOL);
>     virtual HRESULT STDMETHODCALLTYPE spatialNavigationEnabled(_Out_ BOOL*);
>diff --git a/Source/WebKitLegacy/win/WebView.cpp b/Source/WebKitLegacy/win/WebView.cpp
>index d51aa345714..f632efb763b 100644
>--- a/Source/WebKitLegacy/win/WebView.cpp
>+++ b/Source/WebKitLegacy/win/WebView.cpp
>@@ -5297,6 +5297,11 @@ HRESULT WebView::notifyPreferencesChanged(IWebNotification* notification)
>         return hr;
>     settings.setCSSOMViewScrollingAPIEnabled(!!enabled);
> 
>+    hr = prefsPrivate->CSSOMViewSmoothScrollingEnabled(&enabled);
>+    if (FAILED(hr))
>+        return hr;
>+    settings.setCSSOMViewSmoothScrollingEnabled(!!enabled);
>+
>     hr = preferences->privateBrowsingEnabled(&enabled);
>     if (FAILED(hr))
>         return hr;
>diff --git a/Tools/ChangeLog b/Tools/ChangeLog
>index 44ef1c96e14..bec3b4e06dd 100644
>--- a/Tools/ChangeLog
>+++ b/Tools/ChangeLog
>@@ -1,3 +1,14 @@
>+2018-11-06  Frederic Wang  <fwang@igalia.com>
>+
>+        Add support for ScrollOptions' ScrollBehavior and CSS scroll-behavior properties
>+        https://bugs.webkit.org/show_bug.cgi?id=188043
>+
>+        * DumpRenderTree/TestOptions.cpp:
>+        (TestOptions::TestOptions): Parse CSSOMViewSmoothScrollingEnabled.
>+        * DumpRenderTree/TestOptions.h: Add CSSOMViewSmoothScrollingEnabled, disabled by default.
>+        * DumpRenderTree/mac/DumpRenderTree.mm:
>+        (setWebPreferencesForTestOptions): Set CSSOMViewSmoothScrollingEnabled from the test options.
>+
> 2019-06-24  Michael Catanzaro  <mcatanzaro@igalia.com>
> 
>         contributors.json not canonicalized since r243297
>diff --git a/Tools/DumpRenderTree/TestOptions.cpp b/Tools/DumpRenderTree/TestOptions.cpp
>index aaa5e72d4eb..2604e50a9f1 100644
>--- a/Tools/DumpRenderTree/TestOptions.cpp
>+++ b/Tools/DumpRenderTree/TestOptions.cpp
>@@ -117,6 +117,8 @@ TestOptions::TestOptions(const std::string& pathOrURL, const std::string& absolu
>             enableResizeObserver = parseBooleanTestHeaderValue(value);
>         else if (key == "experimental:CoreMathMLEnabled")
>             enableCoreMathML = parseBooleanTestHeaderValue(value);
>+        else if (key == "experimental:CSSOMViewSmoothScrollingEnabled")
>+            enableCSSOMViewSmoothScrolling = parseBooleanTestHeaderValue(value);
>         pairStart = pairEnd + 1;
>     }
> }
>diff --git a/Tools/DumpRenderTree/TestOptions.h b/Tools/DumpRenderTree/TestOptions.h
>index d16f758a366..1f11f35f771 100644
>--- a/Tools/DumpRenderTree/TestOptions.h
>+++ b/Tools/DumpRenderTree/TestOptions.h
>@@ -48,6 +48,7 @@ struct TestOptions {
>     bool adClickAttributionEnabled { false };
>     bool enableResizeObserver { false };
>     bool enableCoreMathML { false };
>+    bool enableCSSOMViewSmoothScrolling { false };
>     std::string jscOptions;
>     std::string additionalSupportedImageTypes;
> 
>diff --git a/Tools/DumpRenderTree/mac/DumpRenderTree.mm b/Tools/DumpRenderTree/mac/DumpRenderTree.mm
>index 6660c32d921..f37c4eff2f4 100644
>--- a/Tools/DumpRenderTree/mac/DumpRenderTree.mm
>+++ b/Tools/DumpRenderTree/mac/DumpRenderTree.mm
>@@ -1022,6 +1022,7 @@ static void setWebPreferencesForTestOptions(const TestOptions& options)
>     preferences.adClickAttributionEnabled = options.adClickAttributionEnabled;
>     preferences.resizeObserverEnabled = options.enableResizeObserver;
>     preferences.coreMathMLEnabled = options.enableCoreMathML;
>+    preferences.CSSOMViewSmoothScrollingEnabled = options.enableCSSOMViewSmoothScrolling;
> }
> 
> // Called once on DumpRenderTree startup.
>-- 
>2.20.1
>

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