Attachment 271444 Details for Bug 154081 – patch

[patch] patch

c-backup.diff (text/plain), 85.01 KB, created by Saam Barati on 2016-02-16 11:13:23 PST

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Creator: Saam Barati

Created: 2016-02-16 11:13:23 PST

Size: 85.01 KB

patch

obsolete

>Index: Source/JavaScriptCore/ChangeLog
>===================================================================
>--- Source/JavaScriptCore/ChangeLog	(revision 196610)
>+++ Source/JavaScriptCore/ChangeLog	(working copy)
>@@ -1,3 +1,148 @@
>+2016-02-15  Saam barati  <sbarati@apple.com>
>+
>+        Implement Proxy [[Get]]
>+        https://bugs.webkit.org/show_bug.cgi?id=154081
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        This patch implements ProxyObject and ProxyConstructor. Their
>+        implementations are straight forward and follow the spec.
>+        The largest change in this patch is adding a second parameter
>+        to PropertySlot's constructor that specifies the trap type of
>+        the getOwnPropertySlot inquiry. Because we overload getOwnPropertySlot
>+        to mean more than operation in the spec, having TrapType gives
>+        getOwnPropertySlot context about the context it's being called in.
>+        TrapType is an enum with the following values:
>+        - Get
>+          This corresponds to [[Get]] in the spec.
>+        - GetOwnProperty
>+          This corresponds to [[GetOwnProperty]] in the spec.
>+        - HasProperty
>+          This corresponds to [[HasProperty]] in the spec.
>+        - VMInquiry
>+          This is basically everything else that isn't one of the above
>+          traps. This value also mandates that getOwnPropertySlot does
>+          not perform any user observable effects. I.e, it can't call
>+          a JS function.
>+
>+        The other non-VMInquiry TrapTypes are allowed to perform user
>+        observable effects. I.e, in future patches, ProxyObject will implement
>+        TrapType::Has and TrapType::GetOwnProperty, which will both be defined
>+        to call user defined JS functions, which clearly have the right to perform
>+        user oversable effects.
>+
>+        We need TrapType to implement the Proxy object because
>+        the Proxy will need to perform different operations depending
>+        on the PropertySlot's TrapType value.
>+
>+        This patch implements getOwnPropertySlot of ProxyObject under
>+        TrapType::Get. 
>+
>+        * API/JSCallbackObjectFunctions.h:
>+        (JSC::JSCallbackObject<Parent>::put):
>+        (JSC::JSCallbackObject<Parent>::staticFunctionGetter):
>+        * JavaScriptCore.xcodeproj/project.pbxproj:
>+        * debugger/DebuggerScope.cpp:
>+        (JSC::DebuggerScope::caughtValue):
>+        * interpreter/Interpreter.cpp:
>+        (JSC::Interpreter::execute):
>+        * jit/JITOperations.cpp:
>+        * llint/LLIntSlowPaths.cpp:
>+        (JSC::LLInt::LLINT_SLOW_PATH_DECL):
>+        * runtime/ArrayPrototype.cpp:
>+        (JSC::getProperty):
>+        * runtime/CommonIdentifiers.h:
>+        * runtime/JSCJSValueInlines.h:
>+        (JSC::JSValue::get):
>+        * runtime/JSFunction.cpp:
>+        (JSC::JSFunction::getOwnNonIndexPropertyNames):
>+        (JSC::JSFunction::put):
>+        (JSC::JSFunction::defineOwnProperty):
>+        * runtime/JSGenericTypedArrayViewConstructorInlines.h:
>+        (JSC::constructGenericTypedArrayViewWithArguments):
>+        * runtime/JSGlobalObject.cpp:
>+        (JSC::JSGlobalObject::init):
>+        (JSC::JSGlobalObject::defineOwnProperty):
>+        * runtime/JSGlobalObject.h:
>+        (JSC::JSGlobalObject::regExpMatchesArrayStructure):
>+        (JSC::JSGlobalObject::moduleRecordStructure):
>+        (JSC::JSGlobalObject::moduleNamespaceObjectStructure):
>+        (JSC::JSGlobalObject::proxyObjectStructure):
>+        (JSC::JSGlobalObject::wasmModuleStructure):
>+        (JSC::JSGlobalObject::hasOwnPropertyForWrite):
>+        * runtime/JSModuleEnvironment.cpp:
>+        (JSC::JSModuleEnvironment::getOwnPropertySlot):
>+        * runtime/JSModuleNamespaceObject.cpp:
>+        (JSC::callbackGetter):
>+        * runtime/JSONObject.cpp:
>+        (JSC::Stringifier::Holder::appendNextProperty):
>+        (JSC::Walker::walk):
>+        * runtime/JSObject.cpp:
>+        (JSC::JSObject::calculatedClassName):
>+        (JSC::JSObject::putDirectNonIndexAccessor):
>+        (JSC::JSObject::hasProperty):
>+        (JSC::JSObject::deleteProperty):
>+        (JSC::JSObject::hasOwnProperty):
>+        (JSC::JSObject::getOwnPropertyDescriptor):
>+        * runtime/JSObject.h:
>+        (JSC::JSObject::getDirectIndex):
>+        (JSC::JSObject::get):
>+        * runtime/JSScope.cpp:
>+        (JSC::abstractAccess):
>+        * runtime/ObjectConstructor.cpp:
>+        (JSC::toPropertyDescriptor):
>+        * runtime/ObjectPrototype.cpp:
>+        (JSC::objectProtoFuncLookupGetter):
>+        (JSC::objectProtoFuncLookupSetter):
>+        (JSC::objectProtoFuncToString):
>+        * runtime/PropertySlot.h:
>+        (JSC::attributesForStructure):
>+        (JSC::PropertySlot::PropertySlot):
>+        (JSC::PropertySlot::isCacheableGetter):
>+        (JSC::PropertySlot::isCacheableCustom):
>+        (JSC::PropertySlot::trapType):
>+        (JSC::PropertySlot::disableCaching):
>+        (JSC::PropertySlot::getValue):
>+        * runtime/ProxyConstructor.cpp: Added.
>+        (JSC::ProxyConstructor::create):
>+        (JSC::ProxyConstructor::ProxyConstructor):
>+        (JSC::ProxyConstructor::finishCreation):
>+        (JSC::constructProxyObject):
>+        (JSC::ProxyConstructor::getConstructData):
>+        (JSC::ProxyConstructor::getCallData):
>+        * runtime/ProxyConstructor.h: Added.
>+        (JSC::ProxyConstructor::createStructure):
>+        * runtime/ProxyObject.cpp: Added.
>+        (JSC::ProxyObject::ProxyObject):
>+        (JSC::ProxyObject::finishCreation):
>+        (JSC::performProxyGet):
>+        (JSC::ProxyObject::getOwnPropertySlotCommon):
>+        (JSC::ProxyObject::getOwnPropertySlot):
>+        (JSC::ProxyObject::getOwnPropertySlotByIndex):
>+        (JSC::ProxyObject::visitChildren):
>+        * runtime/ProxyObject.h: Added.
>+        (JSC::ProxyObject::create):
>+        (JSC::ProxyObject::createStructure):
>+        (JSC::ProxyObject::target):
>+        (JSC::ProxyObject::handler):
>+        * runtime/ReflectObject.cpp:
>+        (JSC::reflectObjectGet):
>+        * runtime/SamplingProfiler.cpp:
>+        (JSC::SamplingProfiler::StackFrame::nameFromCallee):
>+        * tests/stress/proxy-basic.js: Added.
>+        (assert):
>+        (let.handler.get null):
>+        (get let):
>+        (let.handler.get switch):
>+        (let.handler):
>+        * tests/stress/proxy-in-proto-chain.js: Added.
>+        (assert):
>+        * tests/stress/proxy-property-descriptor.js: Added.
>+        (assert):
>+        (set Object):
>+        * wasm/WASMModuleParser.cpp:
>+        (JSC::WASMModuleParser::getImportedValue):
>+
> 2016-02-15  Joseph Pecoraro  <pecoraro@apple.com>
> 
>         Web Inspector: Web Workers have no access to console for debugging
>Index: Source/JavaScriptCore/CMakeLists.txt
>===================================================================
>--- Source/JavaScriptCore/CMakeLists.txt	(revision 196582)
>+++ Source/JavaScriptCore/CMakeLists.txt	(working copy)
>@@ -736,6 +736,8 @@ set(JavaScriptCore_RUNTIME_SOURCES
>     runtime/PropertySlot.cpp
>     runtime/PropertyTable.cpp
>     runtime/PrototypeMap.cpp
>+    runtime/ProxyConstructor.cpp
>+    runtime/ProxyObject.cpp
>     runtime/ReflectObject.cpp
>     runtime/RegExp.cpp
>     runtime/RegExpCache.cpp
>Index: Source/JavaScriptCore/API/JSCallbackObjectFunctions.h
>===================================================================
>--- Source/JavaScriptCore/API/JSCallbackObjectFunctions.h	(revision 196582)
>+++ Source/JavaScriptCore/API/JSCallbackObjectFunctions.h	(working copy)
>@@ -268,7 +268,7 @@ void JSCallbackObject<Parent>::put(JSCel
>             
>             if (OpaqueJSClassStaticFunctionsTable* staticFunctions = jsClass->staticFunctions(exec)) {
>                 if (StaticFunctionEntry* entry = staticFunctions->get(name)) {
>-                    PropertySlot getSlot(thisObject);
>+                    PropertySlot getSlot(thisObject, PropertySlot::TrapType::VMInquiry);
>                     if (Parent::getOwnPropertySlot(thisObject, exec, propertyName, getSlot))
>                         return Parent::put(thisObject, exec, propertyName, value, slot);
>                     if (entry->attributes & kJSPropertyAttributeReadOnly)
>@@ -605,7 +605,7 @@ EncodedJSValue JSCallbackObject<Parent>:
>     JSCallbackObject* thisObj = asCallbackObject(thisValue);
>     
>     // Check for cached or override property.
>-    PropertySlot slot2(thisObj);
>+    PropertySlot slot2(thisObj, PropertySlot::TrapType::VMInquiry);
>     if (Parent::getOwnPropertySlot(thisObj, exec, propertyName, slot2))
>         return JSValue::encode(slot2.getValue(exec, propertyName));
> 
>Index: Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
>===================================================================
>--- Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj	(revision 196582)
>+++ Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj	(working copy)
>@@ -1318,6 +1318,10 @@
> 		797E07A91B8FCFB9008400BA /* JSGlobalLexicalEnvironment.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 797E07A71B8FCFB9008400BA /* JSGlobalLexicalEnvironment.cpp */; };
> 		797E07AA1B8FCFB9008400BA /* JSGlobalLexicalEnvironment.h in Headers */ = {isa = PBXBuildFile; fileRef = 797E07A81B8FCFB9008400BA /* JSGlobalLexicalEnvironment.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		799EF7C41C56ED96002B0534 /* B3PCToOriginMap.h in Headers */ = {isa = PBXBuildFile; fileRef = 799EF7C31C56ED96002B0534 /* B3PCToOriginMap.h */; settings = {ATTRIBUTES = (Private, ); }; };
>+		79B00CBC1C6AB07E0088C65D /* ProxyConstructor.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 79B00CB81C6AB07E0088C65D /* ProxyConstructor.cpp */; };
>+		79B00CBD1C6AB07E0088C65D /* ProxyConstructor.h in Headers */ = {isa = PBXBuildFile; fileRef = 79B00CB91C6AB07E0088C65D /* ProxyConstructor.h */; settings = {ATTRIBUTES = (Private, ); }; };
>+		79B00CBE1C6AB07E0088C65D /* ProxyObject.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 79B00CBA1C6AB07E0088C65D /* ProxyObject.cpp */; };
>+		79B00CBF1C6AB07E0088C65D /* ProxyObject.h in Headers */ = {isa = PBXBuildFile; fileRef = 79B00CBB1C6AB07E0088C65D /* ProxyObject.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		79C4B15D1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 79C4B15B1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.cpp */; };
> 		79C4B15E1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.h in Headers */ = {isa = PBXBuildFile; fileRef = 79C4B15C1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.h */; settings = {ATTRIBUTES = (Private, ); }; };
> 		79CFC6F01C33B10000C768EA /* LLIntPCRanges.h in Headers */ = {isa = PBXBuildFile; fileRef = 79CFC6EF1C33B10000C768EA /* LLIntPCRanges.h */; settings = {ATTRIBUTES = (Private, ); }; };
>@@ -3525,6 +3529,10 @@
> 		797E07A71B8FCFB9008400BA /* JSGlobalLexicalEnvironment.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = JSGlobalLexicalEnvironment.cpp; sourceTree = "<group>"; };
> 		797E07A81B8FCFB9008400BA /* JSGlobalLexicalEnvironment.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = JSGlobalLexicalEnvironment.h; sourceTree = "<group>"; };
> 		799EF7C31C56ED96002B0534 /* B3PCToOriginMap.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = B3PCToOriginMap.h; path = b3/B3PCToOriginMap.h; sourceTree = "<group>"; };
>+		79B00CB81C6AB07E0088C65D /* ProxyConstructor.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ProxyConstructor.cpp; sourceTree = "<group>"; };
>+		79B00CB91C6AB07E0088C65D /* ProxyConstructor.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ProxyConstructor.h; sourceTree = "<group>"; };
>+		79B00CBA1C6AB07E0088C65D /* ProxyObject.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ProxyObject.cpp; sourceTree = "<group>"; };
>+		79B00CBB1C6AB07E0088C65D /* ProxyObject.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ProxyObject.h; sourceTree = "<group>"; };
> 		79C4B15B1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = DFGLiveCatchVariablePreservationPhase.cpp; path = dfg/DFGLiveCatchVariablePreservationPhase.cpp; sourceTree = "<group>"; };
> 		79C4B15C1BA2158F00FD592E /* DFGLiveCatchVariablePreservationPhase.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = DFGLiveCatchVariablePreservationPhase.h; path = dfg/DFGLiveCatchVariablePreservationPhase.h; sourceTree = "<group>"; };
> 		79CFC6EF1C33B10000C768EA /* LLIntPCRanges.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = LLIntPCRanges.h; path = llint/LLIntPCRanges.h; sourceTree = "<group>"; };
>@@ -6008,6 +6016,10 @@
> 				65C02FBB0637462A003E7EE6 /* Protect.h */,
> 				14D844A216AA2C7000A65AF0 /* PrototypeMap.cpp */,
> 				14D844A316AA2C7000A65AF0 /* PrototypeMap.h */,
>+				79B00CB81C6AB07E0088C65D /* ProxyConstructor.cpp */,
>+				79B00CB91C6AB07E0088C65D /* ProxyConstructor.h */,
>+				79B00CBA1C6AB07E0088C65D /* ProxyObject.cpp */,
>+				79B00CBB1C6AB07E0088C65D /* ProxyObject.h */,
> 				0F5780A118FE1E98001E72D9 /* PureNaN.h */,
> 				0F0CD4C015F1A6040032F1C0 /* PutDirectIndexMode.h */,
> 				147B84620E6DE6B1004775A4 /* PutPropertySlot.h */,
>@@ -7061,7 +7073,9 @@
> 				0FEC85761BDACDC70080FF74 /* AirCode.h in Headers */,
> 				0F3730931C0D67EE00052BFA /* AirUseCounts.h in Headers */,
> 				0F4570391BE44C910062A629 /* AirEliminateDeadCode.h in Headers */,
>+				79B00CBD1C6AB07E0088C65D /* ProxyConstructor.h in Headers */,
> 				799EF7C41C56ED96002B0534 /* B3PCToOriginMap.h in Headers */,
>+				79B00CBF1C6AB07E0088C65D /* ProxyObject.h in Headers */,
> 				792CB34A1C4EED5C00D13AF3 /* PCToCodeOriginMap.h in Headers */,
> 				79CFC6F01C33B10000C768EA /* LLIntPCRanges.h in Headers */,
> 				79D5CD5B1C1106A900CECA07 /* SamplingProfiler.h in Headers */,
>@@ -8953,6 +8967,7 @@
> 				A77A423F17A0BBFD00A8DB81 /* DFGClobberize.cpp in Sources */,
> 				A77A424117A0BBFD00A8DB81 /* DFGClobberSet.cpp in Sources */,
> 				0F3C1F1A1B868E7900ABB08B /* DFGClobbersExitState.cpp in Sources */,
>+				79B00CBC1C6AB07E0088C65D /* ProxyConstructor.cpp in Sources */,
> 				0F04396D1B03DC0B009598B7 /* DFGCombinedLiveness.cpp in Sources */,
> 				0FF0F19D16B72A08005DF95B /* DFGCommon.cpp in Sources */,
> 				0FEA0A31170D40BF00BB722C /* DFGCommonData.cpp in Sources */,
>@@ -9014,6 +9029,7 @@
> 				46D4DCBD1C5AB2D500D8D321 /* JSBoundSlotBaseFunction.cpp in Sources */,
> 				0FF2CD5B1B61A4F8004955A8 /* DFGMultiGetByOffsetData.cpp in Sources */,
> 				A737810D1799EA2E00817533 /* DFGNaturalLoops.cpp in Sources */,
>+				79B00CBE1C6AB07E0088C65D /* ProxyObject.cpp in Sources */,
> 				792CB3491C4EED5C00D13AF3 /* PCToCodeOriginMap.cpp in Sources */,
> 				0FF0F19C16B72A03005DF95B /* DFGNode.cpp in Sources */,
> 				0FB3878F1BFBC44D00E3AB1E /* AirOptimizeBlockOrder.cpp in Sources */,
>Index: Source/JavaScriptCore/debugger/DebuggerScope.cpp
>===================================================================
>--- Source/JavaScriptCore/debugger/DebuggerScope.cpp	(revision 196582)
>+++ Source/JavaScriptCore/debugger/DebuggerScope.cpp	(working copy)
>@@ -209,7 +209,7 @@ JSValue DebuggerScope::caughtValue(ExecS
>     SymbolTable* catchSymbolTable = catchEnvironment->symbolTable();
>     RELEASE_ASSERT(catchSymbolTable->size() == 1);
>     PropertyName errorName(catchSymbolTable->begin(catchSymbolTable->m_lock)->key.get());
>-    PropertySlot slot(m_scope.get());
>+    PropertySlot slot(m_scope.get(), PropertySlot::TrapType::Get);
>     bool success = catchEnvironment->getOwnPropertySlot(catchEnvironment, exec, errorName, slot);
>     RELEASE_ASSERT(success && slot.isValue());
>     return slot.getValue(exec, errorName);
>Index: Source/JavaScriptCore/interpreter/Interpreter.cpp
>===================================================================
>--- Source/JavaScriptCore/interpreter/Interpreter.cpp	(revision 196582)
>+++ Source/JavaScriptCore/interpreter/Interpreter.cpp	(working copy)
>@@ -877,7 +877,7 @@ JSValue Interpreter::execute(ProgramExec
>                 switch (JSONPPath[i].m_type) {
>                 case JSONPPathEntryTypeDot: {
>                     if (i == 0) {
>-                        PropertySlot slot(globalObject);
>+                        PropertySlot slot(globalObject, PropertySlot::TrapType::Get);
>                         if (!globalObject->getPropertySlot(callFrame, JSONPPath[i].m_pathEntryName, slot)) {
>                             if (entry)
>                                 return callFrame->vm().throwException(callFrame, createUndefinedVariableError(callFrame, JSONPPath[i].m_pathEntryName));
>@@ -1225,7 +1225,7 @@ JSValue Interpreter::execute(EvalExecuta
>         JSGlobalLexicalEnvironment* globalLexicalEnvironment = jsCast<JSGlobalObject*>(variableObject)->globalLexicalEnvironment();
>         for (unsigned i = 0; i < numVariables; ++i) {
>             const Identifier& ident = codeBlock->variable(i);
>-            PropertySlot slot(globalLexicalEnvironment);
>+            PropertySlot slot(globalLexicalEnvironment, PropertySlot::TrapType::VMInquiry);
>             if (JSGlobalLexicalEnvironment::getOwnPropertySlot(globalLexicalEnvironment, callFrame, ident, slot)) {
>                 return checkedReturn(callFrame->vm().throwException(callFrame,
>                     createTypeError(callFrame, makeString("Can't create duplicate global variable in eval: '", String(ident.impl()), "'"))));
>@@ -1234,7 +1234,7 @@ JSValue Interpreter::execute(EvalExecuta
> 
>         for (int i = 0; i < numFunctions; ++i) {
>             FunctionExecutable* function = codeBlock->functionDecl(i);
>-            PropertySlot slot(globalLexicalEnvironment);
>+            PropertySlot slot(globalLexicalEnvironment, PropertySlot::TrapType::VMInquiry);
>             if (JSGlobalLexicalEnvironment::getOwnPropertySlot(globalLexicalEnvironment, callFrame, function->name(), slot)) {
>                 return checkedReturn(callFrame->vm().throwException(callFrame,
>                     createTypeError(callFrame, makeString("Can't create duplicate global variable in eval: '", String(function->name().impl()), "'"))));
>Index: Source/JavaScriptCore/jit/JITOperations.cpp
>===================================================================
>--- Source/JavaScriptCore/jit/JITOperations.cpp	(revision 196582)
>+++ Source/JavaScriptCore/jit/JITOperations.cpp	(working copy)
>@@ -158,7 +158,7 @@ EncodedJSValue JIT_OPERATION operationGe
>     stubInfo->tookSlowPath = true;
>     
>     JSValue baseValue = JSValue::decode(base);
>-    PropertySlot slot(baseValue);
>+    PropertySlot slot(baseValue, PropertySlot::TrapType::Get);
>     Identifier ident = Identifier::fromUid(vm, uid);
>     return JSValue::encode(baseValue.get(exec, ident, slot));
> }
>@@ -169,7 +169,7 @@ EncodedJSValue JIT_OPERATION operationGe
>     NativeCallFrameTracer tracer(vm, exec);
>     
>     JSValue baseValue = JSValue::decode(base);
>-    PropertySlot slot(baseValue);
>+    PropertySlot slot(baseValue, PropertySlot::TrapType::Get);
>     Identifier ident = Identifier::fromUid(vm, uid);
>     return JSValue::encode(baseValue.get(exec, ident, slot));
> }
>@@ -181,7 +181,7 @@ EncodedJSValue JIT_OPERATION operationGe
>     Identifier ident = Identifier::fromUid(vm, uid);
> 
>     JSValue baseValue = JSValue::decode(base);
>-    PropertySlot slot(baseValue);
>+    PropertySlot slot(baseValue, PropertySlot::TrapType::Get);
>     
>     bool hasResult = baseValue.getPropertySlot(exec, ident, slot);
>     if (stubInfo->considerCaching())
>@@ -203,7 +203,7 @@ EncodedJSValue JIT_OPERATION operationIn
>     AccessType accessType = static_cast<AccessType>(stubInfo->accessType);
> 
>     Identifier ident = Identifier::fromUid(vm, key);
>-    PropertySlot slot(base);
>+    PropertySlot slot(base, PropertySlot::TrapType::HasProperty);
>     bool result = asObject(base)->getPropertySlot(exec, ident, slot);
>     
>     RELEASE_ASSERT(accessType == stubInfo->accessType);
>@@ -1885,7 +1885,7 @@ EncodedJSValue JIT_OPERATION operationGe
>     // ModuleVar is always converted to ClosureVar for get_from_scope.
>     ASSERT(getPutInfo.resolveType() != ModuleVar);
> 
>-    PropertySlot slot(scope);
>+    PropertySlot slot(scope, PropertySlot::TrapType::Get);
>     if (!scope->getPropertySlot(exec, ident, slot)) {
>         if (getPutInfo.resolveMode() == ThrowIfNotFound)
>             vm.throwException(exec, createUndefinedVariableError(exec, ident));
>@@ -1937,7 +1937,7 @@ void JIT_OPERATION operationPutToScope(E
>         && jsDynamicCast<JSGlobalLexicalEnvironment*>(scope)
>         && getPutInfo.initializationMode() != Initialization) {
>         // When we can't statically prove we need a TDZ check, we must perform the check on the slow path.
>-        PropertySlot slot(scope);
>+        PropertySlot slot(scope, PropertySlot::TrapType::Get);
>         JSGlobalLexicalEnvironment::getOwnPropertySlot(scope, exec, ident, slot);
>         if (slot.getValue(exec, ident) == jsTDZValue()) {
>             exec->vm().throwException(exec, createTDZError(exec));
>Index: Source/JavaScriptCore/llint/LLIntSlowPaths.cpp
>===================================================================
>--- Source/JavaScriptCore/llint/LLIntSlowPaths.cpp	(revision 196582)
>+++ Source/JavaScriptCore/llint/LLIntSlowPaths.cpp	(working copy)
>@@ -551,7 +551,7 @@ LLINT_SLOW_PATH_DECL(slow_path_get_by_id
>     CodeBlock* codeBlock = exec->codeBlock();
>     const Identifier& ident = codeBlock->identifier(pc[3].u.operand);
>     JSValue baseValue = LLINT_OP_C(2).jsValue();
>-    PropertySlot slot(baseValue);
>+    PropertySlot slot(baseValue, PropertySlot::PropertySlot::TrapType::Get);
> 
>     JSValue result = baseValue.get(exec, ident, slot);
>     LLINT_CHECK_EXCEPTION();
>@@ -602,7 +602,7 @@ LLINT_SLOW_PATH_DECL(slow_path_get_argum
>     CodeBlock* codeBlock = exec->codeBlock();
>     const Identifier& ident = codeBlock->identifier(pc[3].u.operand);
>     JSValue baseValue = LLINT_OP(2).jsValue();
>-    PropertySlot slot(baseValue);
>+    PropertySlot slot(baseValue, PropertySlot::TrapType::Get);
>     LLINT_RETURN(baseValue.get(exec, ident, slot));
> }
> 
>@@ -1413,7 +1413,7 @@ LLINT_SLOW_PATH_DECL(slow_path_get_from_
>     // ModuleVar is always converted to ClosureVar for get_from_scope.
>     ASSERT(getPutInfo.resolveType() != ModuleVar);
> 
>-    PropertySlot slot(scope);
>+    PropertySlot slot(scope, PropertySlot::TrapType::Get);
>     if (!scope->getPropertySlot(exec, ident, slot)) {
>         if (getPutInfo.resolveMode() == ThrowIfNotFound)
>             LLINT_RETURN(exec->vm().throwException(exec, createUndefinedVariableError(exec, ident)));
>@@ -1461,7 +1461,7 @@ LLINT_SLOW_PATH_DECL(slow_path_put_to_sc
>         && jsDynamicCast<JSGlobalLexicalEnvironment*>(scope)
>         && getPutInfo.initializationMode() != Initialization) {
>         // When we can't statically prove we need a TDZ check, we must perform the check on the slow path.
>-        PropertySlot slot(scope);
>+        PropertySlot slot(scope, PropertySlot::TrapType::Get);
>         JSGlobalLexicalEnvironment::getOwnPropertySlot(scope, exec, ident, slot);
>         if (slot.getValue(exec, ident) == jsTDZValue())
>             LLINT_THROW(createTDZError(exec));
>Index: Source/JavaScriptCore/runtime/ArrayPrototype.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ArrayPrototype.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/ArrayPrototype.cpp	(working copy)
>@@ -151,7 +151,7 @@ static ALWAYS_INLINE JSValue getProperty
> {
>     if (JSValue result = object->tryGetIndexQuickly(index))
>         return result;
>-    PropertySlot slot(object);
>+    PropertySlot slot(object, PropertySlot::TrapType::Get);
>     if (!object->getPropertySlot(exec, index, slot))
>         return JSValue();
>     return slot.getValue(exec, index);
>Index: Source/JavaScriptCore/runtime/CommonIdentifiers.h
>===================================================================
>--- Source/JavaScriptCore/runtime/CommonIdentifiers.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/CommonIdentifiers.h	(working copy)
>@@ -52,6 +52,7 @@
>     macro(NumberFormat) \
>     macro(Object) \
>     macro(Promise) \
>+    macro(Proxy) \
>     macro(RangeError) \
>     macro(ReferenceError) \
>     macro(Reflect) \
>Index: Source/JavaScriptCore/runtime/JSCJSValueInlines.h
>===================================================================
>--- Source/JavaScriptCore/runtime/JSCJSValueInlines.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSCJSValueInlines.h	(working copy)
>@@ -705,7 +705,7 @@ inline JSValue JSValue::toThis(ExecState
> 
> ALWAYS_INLINE JSValue JSValue::get(ExecState* exec, PropertyName propertyName) const
> {
>-    PropertySlot slot(asValue());
>+    PropertySlot slot(asValue(), PropertySlot::TrapType::Get);
>     return get(exec, propertyName, slot);
> }
> 
>@@ -732,7 +732,7 @@ ALWAYS_INLINE bool JSValue::getPropertyS
> 
> ALWAYS_INLINE JSValue JSValue::get(ExecState* exec, unsigned propertyName) const
> {
>-    PropertySlot slot(asValue());
>+    PropertySlot slot(asValue(), PropertySlot::TrapType::Get);
>     return get(exec, propertyName, slot);
> }
> 
>Index: Source/JavaScriptCore/runtime/JSFunction.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSFunction.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSFunction.cpp	(working copy)
>@@ -430,7 +430,7 @@ void JSFunction::getOwnNonIndexPropertyN
>     if (!thisObject->isHostOrBuiltinFunction() && mode.includeDontEnumProperties()) {
>         VM& vm = exec->vm();
>         // Make sure prototype has been reified.
>-        PropertySlot slot(thisObject);
>+        PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>         thisObject->methodTable(vm)->getOwnPropertySlot(thisObject, exec, vm.propertyNames->prototype, slot);
> 
>         propertyNames.add(vm.propertyNames->arguments);
>@@ -451,7 +451,7 @@ void JSFunction::put(JSCell* cell, ExecS
>     if (propertyName == exec->propertyNames().prototype) {
>         // Make sure prototype has been reified, such that it can only be overwritten
>         // following the rules set out in ECMA-262 8.12.9.
>-        PropertySlot slot(thisObject);
>+        PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>         thisObject->methodTable(exec->vm())->getOwnPropertySlot(thisObject, exec, propertyName, slot);
>         if (thisObject->m_rareData)
>             thisObject->m_rareData->clear("Store to prototype property of a function");
>@@ -501,7 +501,7 @@ bool JSFunction::defineOwnProperty(JSObj
>     if (propertyName == exec->propertyNames().prototype) {
>         // Make sure prototype has been reified, such that it can only be overwritten
>         // following the rules set out in ECMA-262 8.12.9.
>-        PropertySlot slot(thisObject);
>+        PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>         thisObject->methodTable(exec->vm())->getOwnPropertySlot(thisObject, exec, propertyName, slot);
>         if (thisObject->m_rareData)
>             thisObject->m_rareData->clear("Store to prototype property of a function");
>@@ -511,7 +511,7 @@ bool JSFunction::defineOwnProperty(JSObj
>     bool valueCheck;
>     if (propertyName == exec->propertyNames().arguments) {
>         if (thisObject->jsExecutable()->isStrictMode()) {
>-            PropertySlot slot(thisObject);
>+            PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>             if (!Base::getOwnPropertySlot(thisObject, exec, propertyName, slot))
>                 thisObject->putDirectAccessor(exec, propertyName, thisObject->globalObject()->throwTypeErrorGetterSetter(exec->vm()), DontDelete | DontEnum | Accessor);
>             return Base::defineOwnProperty(object, exec, propertyName, descriptor, throwException);
>@@ -519,7 +519,7 @@ bool JSFunction::defineOwnProperty(JSObj
>         valueCheck = !descriptor.value() || sameValue(exec, descriptor.value(), retrieveArguments(exec, thisObject));
>     } else if (propertyName == exec->propertyNames().caller) {
>         if (thisObject->jsExecutable()->isStrictMode()) {
>-            PropertySlot slot(thisObject);
>+            PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>             if (!Base::getOwnPropertySlot(thisObject, exec, propertyName, slot))
>                 thisObject->putDirectAccessor(exec, propertyName, thisObject->globalObject()->throwTypeErrorGetterSetter(exec->vm()), DontDelete | DontEnum | Accessor);
>             return Base::defineOwnProperty(object, exec, propertyName, descriptor, throwException);
>Index: Source/JavaScriptCore/runtime/JSGenericTypedArrayViewConstructorInlines.h
>===================================================================
>--- Source/JavaScriptCore/runtime/JSGenericTypedArrayViewConstructorInlines.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSGenericTypedArrayViewConstructorInlines.h	(working copy)
>@@ -150,7 +150,7 @@ static JSObject* constructGenericTypedAr
>         if (isTypedView(object->classInfo()->typedArrayStorageType))
>             length = jsCast<JSArrayBufferView*>(object)->length();
>         else {
>-            PropertySlot lengthSlot(object);
>+            PropertySlot lengthSlot(object, PropertySlot::TrapType::Get);
>             object->getPropertySlot(exec, vm.propertyNames->length, lengthSlot);
> 
>             JSValue iteratorFunc = object->get(exec, vm.propertyNames->iteratorSymbol);
>Index: Source/JavaScriptCore/runtime/JSGlobalObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSGlobalObject.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSGlobalObject.cpp	(working copy)
>@@ -128,6 +128,8 @@
> #include "ObjectConstructor.h"
> #include "ObjectPrototype.h"
> #include "ParserError.h"
>+#include "ProxyConstructor.h"
>+#include "ProxyObject.h"
> #include "ReflectObject.h"
> #include "RegExpConstructor.h"
> #include "RegExpMatchesArray.h"
>@@ -366,6 +368,7 @@ void JSGlobalObject::init(VM& vm)
> 
>     m_moduleRecordStructure.set(vm, this, JSModuleRecord::createStructure(vm, this, m_objectPrototype.get()));
>     m_moduleNamespaceObjectStructure.set(vm, this, JSModuleNamespaceObject::createStructure(vm, this, jsNull()));
>+    m_proxyObjectStructure.set(vm, this, ProxyObject::createStructure(vm, this, m_objectPrototype.get()));
>     
> #if ENABLE(WEBASSEMBLY)
>     m_wasmModuleStructure.set(vm, this, JSWASMModule::createStructure(vm, this));
>@@ -454,6 +457,8 @@ m_ ## lowerName ## Prototype->putDirectW
>     putDirectWithoutTransition(vm, vm.propertyNames->SyntaxError, m_syntaxErrorConstructor.get(), DontEnum);
>     putDirectWithoutTransition(vm, vm.propertyNames->TypeError, m_typeErrorConstructor.get(), DontEnum);
>     putDirectWithoutTransition(vm, vm.propertyNames->URIError, m_URIErrorConstructor.get(), DontEnum);
>+
>+    putDirectWithoutTransition(vm, vm.propertyNames->Proxy, ProxyConstructor::create(vm, ProxyConstructor::createStructure(vm, this, m_functionPrototype.get())), DontEnum);
>     
>     
> #define PUT_CONSTRUCTOR_FOR_SIMPLE_TYPE(capitalName, lowerName, properName, instanceType, jsName) \
>@@ -626,7 +631,7 @@ void JSGlobalObject::put(JSCell* cell, E
> bool JSGlobalObject::defineOwnProperty(JSObject* object, ExecState* exec, PropertyName propertyName, const PropertyDescriptor& descriptor, bool shouldThrow)
> {
>     JSGlobalObject* thisObject = jsCast<JSGlobalObject*>(object);
>-    PropertySlot slot(thisObject);
>+    PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>     // silently ignore attempts to add accessors aliasing vars.
>     if (descriptor.isAccessorDescriptor() && symbolTableGet(thisObject, propertyName, slot))
>         return false;
>Index: Source/JavaScriptCore/runtime/JSGlobalObject.h
>===================================================================
>--- Source/JavaScriptCore/runtime/JSGlobalObject.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSGlobalObject.h	(working copy)
>@@ -277,6 +277,7 @@ protected:
>     WriteBarrier<Structure> m_regExpMatchesArrayStructure;
>     WriteBarrier<Structure> m_moduleRecordStructure;
>     WriteBarrier<Structure> m_moduleNamespaceObjectStructure;
>+    WriteBarrier<Structure> m_proxyObjectStructure;
> #if ENABLE(WEBASSEMBLY)
>     WriteBarrier<Structure> m_wasmModuleStructure;
> #endif
>@@ -529,6 +530,7 @@ public:
>     Structure* regExpMatchesArrayStructure() const { return m_regExpMatchesArrayStructure.get(); }
>     Structure* moduleRecordStructure() const { return m_moduleRecordStructure.get(); }
>     Structure* moduleNamespaceObjectStructure() const { return m_moduleNamespaceObjectStructure.get(); }
>+    Structure* proxyObjectStructure() const { return m_proxyObjectStructure.get(); }
> #if ENABLE(WEBASSEMBLY)
>     Structure* wasmModuleStructure() const { return m_wasmModuleStructure.get(); }
> #endif
>@@ -719,7 +721,7 @@ inline JSGlobalObject* asGlobalObject(JS
> 
> inline bool JSGlobalObject::hasOwnPropertyForWrite(ExecState* exec, PropertyName propertyName)
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::VMInquiry);
>     if (Base::getOwnPropertySlot(this, exec, propertyName, slot))
>         return true;
>     bool slotIsWriteable;
>Index: Source/JavaScriptCore/runtime/JSModuleEnvironment.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSModuleEnvironment.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSModuleEnvironment.cpp	(working copy)
>@@ -83,7 +83,7 @@ bool JSModuleEnvironment::getOwnProperty
>     if (resolution.type == JSModuleRecord::Resolution::Type::Resolved) {
>         // When resolveImport resolves the resolution, the imported module environment must have the binding.
>         JSModuleEnvironment* importedModuleEnvironment = resolution.moduleRecord->moduleEnvironment();
>-        PropertySlot redirectSlot(importedModuleEnvironment);
>+        PropertySlot redirectSlot(importedModuleEnvironment, PropertySlot::TrapType::Get);
>         bool result = importedModuleEnvironment->methodTable(exec->vm())->getOwnPropertySlot(importedModuleEnvironment, exec, resolution.localName, redirectSlot);
>         ASSERT_UNUSED(result, result);
>         ASSERT(redirectSlot.isValue());
>Index: Source/JavaScriptCore/runtime/JSModuleNamespaceObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSModuleNamespaceObject.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSModuleNamespaceObject.cpp	(working copy)
>@@ -106,7 +106,7 @@ static EncodedJSValue callbackGetter(Exe
>     JSModuleRecord* targetModule = resolution.moduleRecord;
>     JSModuleEnvironment* targetEnvironment = targetModule->moduleEnvironment();
> 
>-    PropertySlot trampolineSlot(targetEnvironment);
>+    PropertySlot trampolineSlot(targetEnvironment, PropertySlot::TrapType::Get);
>     if (!targetEnvironment->methodTable(exec->vm())->getOwnPropertySlot(targetEnvironment, exec, resolution.localName, trampolineSlot))
>         return JSValue::encode(jsUndefined());
> 
>Index: Source/JavaScriptCore/runtime/JSONObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSONObject.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSONObject.cpp	(working copy)
>@@ -466,7 +466,7 @@ bool Stringifier::Holder::appendNextProp
>         if (m_isJSArray && asArray(m_object.get())->canGetIndexQuickly(index))
>             value = asArray(m_object.get())->getIndexQuickly(index);
>         else {
>-            PropertySlot slot(m_object.get());
>+            PropertySlot slot(m_object.get(), PropertySlot::TrapType::Get);
>             if (m_object->methodTable()->getOwnPropertySlotByIndex(m_object.get(), exec, index, slot)) {
>                 value = slot.getValue(exec, index);
>                 if (exec->hadException())
>@@ -484,7 +484,7 @@ bool Stringifier::Holder::appendNextProp
>         stringifyResult = stringifier.appendStringifiedValue(builder, value, m_object.get(), index);
>     } else {
>         // Get the value.
>-        PropertySlot slot(m_object.get());
>+        PropertySlot slot(m_object.get(), PropertySlot::TrapType::Get);
>         Identifier& propertyName = m_propertyNames->propertyNameVector()[index];
>         if (!m_object->methodTable()->getOwnPropertySlot(m_object.get(), exec, propertyName, slot))
>             return true;
>@@ -618,7 +618,7 @@ NEVER_INLINE JSValue Walker::walk(JSValu
>                 if (isJSArray(array) && array->canGetIndexQuickly(index))
>                     inValue = array->getIndexQuickly(index);
>                 else {
>-                    PropertySlot slot(array);
>+                    PropertySlot slot(array, PropertySlot::TrapType::Get);
>                     if (array->methodTable()->getOwnPropertySlotByIndex(array, m_exec, index, slot))
>                         inValue = slot.getValue(m_exec, index);
>                     else
>@@ -670,7 +670,7 @@ NEVER_INLINE JSValue Walker::walk(JSValu
>                     propertyStack.removeLast();
>                     break;
>                 }
>-                PropertySlot slot(object);
>+                PropertySlot slot(object, PropertySlot::TrapType::Get);
>                 if (object->methodTable()->getOwnPropertySlot(object, m_exec, properties[index], slot))
>                     inValue = slot.getValue(m_exec, properties[index]);
>                 else
>Index: Source/JavaScriptCore/runtime/JSObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSObject.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSObject.cpp	(working copy)
>@@ -264,7 +264,7 @@ String JSObject::calculatedClassName(JSO
> {
>     String prototypeFunctionName;
>     ExecState* exec = object->globalObject()->globalExec();
>-    PropertySlot slot(object->structure()->storedPrototype());
>+    PropertySlot slot(object->structure()->storedPrototype(), PropertySlot::TrapType::VMInquiry);
>     PropertyName constructor(exec->propertyNames().constructor);
>     if (object->getPropertySlot(exec, constructor, slot)) {
>         if (slot.isValue()) {
>@@ -1270,15 +1270,17 @@ void JSObject::putDirectNonIndexAccessor
>     structure->setHasGetterSetterPropertiesWithProtoCheck(propertyName == vm.propertyNames->underscoreProto);
> }
> 
>+// HasProperty(O, P) from Section 7.3.10 of the spec.
>+// http://www.ecma-international.org/ecma-262/6.0/index.html#sec-hasproperty
> bool JSObject::hasProperty(ExecState* exec, PropertyName propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::HasProperty);
>     return const_cast<JSObject*>(this)->getPropertySlot(exec, propertyName, slot);
> }
> 
> bool JSObject::hasProperty(ExecState* exec, unsigned propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::HasProperty);
>     return const_cast<JSObject*>(this)->getPropertySlot(exec, propertyName, slot);
> }
> 
>@@ -1304,15 +1306,17 @@ bool JSObject::deleteProperty(JSCell* ce
>     return true;
> }
> 
>+// HasOwnProperty(O, P) from section 7.3.11 in the spec.
>+// http://www.ecma-international.org/ecma-262/6.0/index.html#sec-hasownproperty
> bool JSObject::hasOwnProperty(ExecState* exec, PropertyName propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::GetOwnProperty);
>     return const_cast<JSObject*>(this)->methodTable(exec->vm())->getOwnPropertySlot(const_cast<JSObject*>(this), exec, propertyName, slot);
> }
> 
> bool JSObject::hasOwnProperty(ExecState* exec, unsigned propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::GetOwnProperty);
>     return const_cast<JSObject*>(this)->methodTable(exec->vm())->getOwnPropertySlotByIndex(const_cast<JSObject*>(this), exec, propertyName, slot);
> }
> 
>@@ -2548,7 +2552,7 @@ static JSBoundSlotBaseFunction* getBound
> 
> bool JSObject::getOwnPropertyDescriptor(ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor)
> {
>-    JSC::PropertySlot slot(this);
>+    JSC::PropertySlot slot(this, PropertySlot::TrapType::GetOwnProperty);
>     if (!methodTable(exec->vm())->getOwnPropertySlot(this, exec, propertyName, slot))
>         return false;
> 
>Index: Source/JavaScriptCore/runtime/JSObject.h
>===================================================================
>--- Source/JavaScriptCore/runtime/JSObject.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSObject.h	(working copy)
>@@ -266,7 +266,7 @@ public:
>     {
>         if (JSValue result = tryGetIndexQuickly(i))
>             return result;
>-        PropertySlot slot(this);
>+        PropertySlot slot(this, PropertySlot::TrapType::Get);
>         if (methodTable(exec->vm())->getOwnPropertySlotByIndex(this, exec, i, slot))
>             return slot.getValue(exec, i);
>         return JSValue();
>@@ -1190,7 +1190,7 @@ ALWAYS_INLINE bool JSObject::getProperty
> 
> inline JSValue JSObject::get(ExecState* exec, PropertyName propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::Get);
>     if (const_cast<JSObject*>(this)->getPropertySlot(exec, propertyName, slot))
>         return slot.getValue(exec, propertyName);
>     
>@@ -1199,7 +1199,7 @@ inline JSValue JSObject::get(ExecState* 
> 
> inline JSValue JSObject::get(ExecState* exec, unsigned propertyName) const
> {
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::Get);
>     if (const_cast<JSObject*>(this)->getPropertySlot(exec, propertyName, slot))
>         return slot.getValue(exec, propertyName);
> 
>Index: Source/JavaScriptCore/runtime/JSScope.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/JSScope.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/JSScope.cpp	(working copy)
>@@ -127,7 +127,7 @@ static inline bool abstractAccess(ExecSt
>             return true;
>         }
> 
>-        PropertySlot slot(globalObject);
>+        PropertySlot slot(globalObject, PropertySlot::TrapType::VMInquiry);
>         bool hasOwnProperty = globalObject->getOwnPropertySlot(globalObject, exec, ident, slot);
>         if (!hasOwnProperty) {
>             op = ResolveOp(makeType(UnresolvedProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0);
>Index: Source/JavaScriptCore/runtime/ObjectConstructor.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ObjectConstructor.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/ObjectConstructor.cpp	(working copy)
>@@ -331,14 +331,14 @@ bool toPropertyDescriptor(ExecState* exe
>     }
>     JSObject* description = asObject(in);
> 
>-    PropertySlot enumerableSlot(description);
>+    PropertySlot enumerableSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().enumerable, enumerableSlot)) {
>         desc.setEnumerable(enumerableSlot.getValue(exec, exec->propertyNames().enumerable).toBoolean(exec));
>         if (exec->hadException())
>             return false;
>     }
> 
>-    PropertySlot configurableSlot(description);
>+    PropertySlot configurableSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().configurable, configurableSlot)) {
>         desc.setConfigurable(configurableSlot.getValue(exec, exec->propertyNames().configurable).toBoolean(exec));
>         if (exec->hadException())
>@@ -346,21 +346,21 @@ bool toPropertyDescriptor(ExecState* exe
>     }
> 
>     JSValue value;
>-    PropertySlot valueSlot(description);
>+    PropertySlot valueSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().value, valueSlot)) {
>         desc.setValue(valueSlot.getValue(exec, exec->propertyNames().value));
>         if (exec->hadException())
>             return false;
>     }
> 
>-    PropertySlot writableSlot(description);
>+    PropertySlot writableSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().writable, writableSlot)) {
>         desc.setWritable(writableSlot.getValue(exec, exec->propertyNames().writable).toBoolean(exec));
>         if (exec->hadException())
>             return false;
>     }
> 
>-    PropertySlot getSlot(description);
>+    PropertySlot getSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().get, getSlot)) {
>         JSValue get = getSlot.getValue(exec, exec->propertyNames().get);
>         if (exec->hadException())
>@@ -375,7 +375,7 @@ bool toPropertyDescriptor(ExecState* exe
>         desc.setGetter(get);
>     }
> 
>-    PropertySlot setSlot(description);
>+    PropertySlot setSlot(description, PropertySlot::TrapType::HasProperty);
>     if (description->getPropertySlot(exec, exec->propertyNames().set, setSlot)) {
>         JSValue set = setSlot.getValue(exec, exec->propertyNames().set);
>         if (exec->hadException())
>Index: Source/JavaScriptCore/runtime/ObjectPrototype.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ObjectPrototype.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/ObjectPrototype.cpp	(working copy)
>@@ -174,7 +174,7 @@ EncodedJSValue JSC_HOST_CALL objectProto
>     if (exec->hadException())
>         return JSValue::encode(jsUndefined());
> 
>-    PropertySlot slot(thisObject);
>+    PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>     if (thisObject->getPropertySlot(exec, propertyName, slot)) {
>         if (slot.isAccessor()) {
>             GetterSetter* getterSetter = slot.getterSetter();
>@@ -201,7 +201,7 @@ EncodedJSValue JSC_HOST_CALL objectProto
>     if (exec->hadException())
>         return JSValue::encode(jsUndefined());
> 
>-    PropertySlot slot(thisObject);
>+    PropertySlot slot(thisObject, PropertySlot::TrapType::VMInquiry);
>     if (thisObject->getPropertySlot(exec, propertyName, slot)) {
>         if (slot.isAccessor()) {
>             GetterSetter* getterSetter = slot.getterSetter();
>@@ -264,7 +264,7 @@ EncodedJSValue JSC_HOST_CALL objectProto
>     JSString* result = thisObject->structure(vm)->objectToStringValue();
>     if (!result) {
>         PropertyName toStringTagSymbol = exec->propertyNames().toStringTagSymbol;
>-        PropertySlot toStringTagSlot(thisObject);
>+        PropertySlot toStringTagSlot(thisObject, PropertySlot::TrapType::Get);
>         if (thisObject->getPropertySlot(exec, toStringTagSymbol, toStringTagSlot)) {
>             JSValue stringTag = toStringTagSlot.getValue(exec, toStringTagSymbol);
>             if (stringTag.isString()) {
>Index: Source/JavaScriptCore/runtime/PropertySlot.h
>===================================================================
>--- Source/JavaScriptCore/runtime/PropertySlot.h	(revision 196582)
>+++ Source/JavaScriptCore/runtime/PropertySlot.h	(working copy)
>@@ -59,27 +59,36 @@ inline unsigned attributesForStructure(u
> }
> 
> class PropertySlot {
>-    enum PropertyType {
>+    enum PropertyType : uint8_t {
>         TypeUnset,
>         TypeValue,
>         TypeGetter,
>         TypeCustom
>     };
> 
>-    enum CacheabilityType {
>+    enum CacheabilityType : uint8_t {
>         CachingDisallowed,
>         CachingAllowed
>     };
> 
> public:
>-    explicit PropertySlot(const JSValue thisValue)
>+    enum class TrapType : uint8_t {
>+        Get, // [[Get]] in the spec.
>+        HasProperty, // [[HasProperty]] in the spec.
>+        GetOwnProperty, // [[GetOwnProperty]] in the spec.
>+        VMInquiry, // Our VM is just poking around. When this is the TrapType, getOwnPropertySlot is not allowed to do user observable actions.
>+    };
>+
>+    explicit PropertySlot(const JSValue thisValue, TrapType trapType)
>         : m_propertyType(TypeUnset)
>         , m_offset(invalidOffset)
>         , m_thisValue(thisValue)
>         , m_slotBase(nullptr)
>         , m_watchpointSet(nullptr)
>         , m_cacheability(CachingAllowed)
>+        , m_trapType(trapType)
>     {
>+        UNUSED_PARAM(m_trapType);
>     }
> 
>     typedef EncodedJSValue (*GetValueFunc)(ExecState*, EncodedJSValue thisValue, PropertyName);
>@@ -96,6 +105,8 @@ public:
>     bool isCacheableGetter() const { return isCacheable() && isAccessor(); }
>     bool isCacheableCustom() const { return isCacheable() && isCustom(); }
> 
>+    TrapType trapType() const { return m_trapType; }
>+
>     void disableCaching()
>     {
>         m_cacheability = CachingDisallowed;
>@@ -268,6 +279,7 @@ private:
>     JSObject* m_slotBase;
>     WatchpointSet* m_watchpointSet;
>     CacheabilityType m_cacheability;
>+    TrapType m_trapType;
> };
> 
> ALWAYS_INLINE JSValue PropertySlot::getValue(ExecState* exec, PropertyName propertyName) const
>Index: Source/JavaScriptCore/runtime/ProxyConstructor.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ProxyConstructor.cpp	(revision 0)
>+++ Source/JavaScriptCore/runtime/ProxyConstructor.cpp	(working copy)
>@@ -0,0 +1,87 @@
>+/*
>+ * Copyright (C) 2016 Apple Inc. All Rights Reserved.
>+ *
>+ * Redistribution and use in source and binary forms, with or without
>+ * modification, are permitted provided that the following conditions
>+ * are met:
>+ * 1. Redistributions of source code must retain the above copyright
>+ *    notice, this list of conditions and the following disclaimer.
>+ * 2. Redistributions in binary form must reproduce the above copyright
>+ *    notice, this list of conditions and the following disclaimer in the
>+ *    documentation and/or other materials provided with the distribution.
>+ *
>+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
>+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
>+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
>+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
>+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
>+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
>+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
>+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
>+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>+ */
>+
>+#include "config.h"
>+#include "ProxyConstructor.h"
>+
>+#include "Error.h"
>+#include "JSCJSValueInlines.h"
>+#include "JSCellInlines.h"
>+#include "ProxyObject.h"
>+#include "ObjectPrototype.h"
>+#include "StructureInlines.h"
>+
>+namespace JSC {
>+
>+STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(ProxyConstructor);
>+
>+const ClassInfo ProxyConstructor::s_info = { "Proxy", &Base::s_info, 0, CREATE_METHOD_TABLE(ProxyConstructor) };
>+
>+ProxyConstructor* ProxyConstructor::create(VM& vm, Structure* structure)
>+{
>+    ProxyConstructor* constructor = new (NotNull, allocateCell<ProxyConstructor>(vm.heap)) ProxyConstructor(vm, structure);
>+    constructor->finishCreation(vm, "Proxy");
>+    return constructor;
>+}
>+
>+ProxyConstructor::ProxyConstructor(VM& vm, Structure* structure)
>+    : Base(vm, structure)
>+{
>+}
>+
>+void ProxyConstructor::finishCreation(VM& vm, const char* name)
>+{
>+    Base::finishCreation(vm, name);
>+
>+    putDirectWithoutTransition(vm, vm.propertyNames->length, jsNumber(2), ReadOnly | DontDelete | DontEnum);
>+}
>+
>+static EncodedJSValue JSC_HOST_CALL constructProxyObject(ExecState* exec)
>+{
>+    if (exec->newTarget().isUndefined())
>+        return throwVMTypeError(exec, ASCIILiteral("new.target of Proxy construct should not be undefined."));
>+
>+    ArgList args(exec);
>+    JSValue target = args.at(0);
>+    JSValue handler = args.at(1);
>+    return JSValue::encode(ProxyObject::create(exec, exec->lexicalGlobalObject()->proxyObjectStructure(), target, handler));
>+}
>+
>+ConstructType ProxyConstructor::getConstructData(JSCell*, ConstructData& constructData)
>+{
>+    constructData.native.function = constructProxyObject;
>+    return ConstructTypeHost;
>+}
>+
>+CallType ProxyConstructor::getCallData(JSCell*, CallData& callData)
>+{
>+    // Proxy should throw a TypeError when called as a function.
>+    callData.js.functionExecutable = 0;
>+    callData.js.scope = 0;
>+    callData.native.function = 0;
>+    return CallTypeNone;
>+}
>+
>+} // namespace JSC
>Index: Source/JavaScriptCore/runtime/ProxyConstructor.h
>===================================================================
>--- Source/JavaScriptCore/runtime/ProxyConstructor.h	(revision 0)
>+++ Source/JavaScriptCore/runtime/ProxyConstructor.h	(working copy)
>@@ -0,0 +1,59 @@
>+/*
>+ * Copyright (C) 2016 Apple Inc. All Rights Reserved.
>+ *
>+ * Redistribution and use in source and binary forms, with or without
>+ * modification, are permitted provided that the following conditions
>+ * are met:
>+ * 1. Redistributions of source code must retain the above copyright
>+ *    notice, this list of conditions and the following disclaimer.
>+ * 2. Redistributions in binary form must reproduce the above copyright
>+ *    notice, this list of conditions and the following disclaimer in the
>+ *    documentation and/or other materials provided with the distribution.
>+ *
>+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
>+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
>+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
>+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
>+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
>+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
>+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
>+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
>+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>+ */
>+
>+#ifndef ProxyConstructor_h
>+#define ProxyConstructor_h
>+
>+#include "InternalFunction.h"
>+
>+namespace JSC {
>+
>+class ProxyConstructor : public InternalFunction {
>+public:
>+    typedef InternalFunction Base;
>+    static const unsigned StructureFlags = Base::StructureFlags;
>+
>+    static ProxyConstructor* create(VM& vm, Structure* structure);
>+
>+    DECLARE_INFO;
>+
>+    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype) 
>+    { 
>+        return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info()); 
>+    }
>+
>+    void finishCreation(VM& vm, const char* name);
>+
>+private:
>+    ProxyConstructor(VM&, Structure*);
>+    static ConstructType getConstructData(JSCell*, ConstructData&);
>+    static CallType getCallData(JSCell*, CallData&);
>+
>+    static EncodedJSValue getGetter(ExecState*, EncodedJSValue thisValue, PropertyName);
>+};
>+
>+} // namespace JSC
>+
>+#endif // ProxyConstructor_h
>Index: Source/JavaScriptCore/runtime/ProxyObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ProxyObject.cpp	(revision 0)
>+++ Source/JavaScriptCore/runtime/ProxyObject.cpp	(working copy)
>@@ -0,0 +1,172 @@
>+/*
>+ * Copyright (C) 2016 Apple Inc. All Rights Reserved.
>+ *
>+ * Redistribution and use in source and binary forms, with or without
>+ * modification, are permitted provided that the following conditions
>+ * are met:
>+ * 1. Redistributions of source code must retain the above copyright
>+ *    notice, this list of conditions and the following disclaimer.
>+ * 2. Redistributions in binary form must reproduce the above copyright
>+ *    notice, this list of conditions and the following disclaimer in the
>+ *    documentation and/or other materials provided with the distribution.
>+ *
>+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
>+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
>+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
>+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
>+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
>+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
>+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
>+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
>+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>+ */
>+
>+#include "config.h"
>+#include "ProxyObject.h"
>+
>+//#include "JSCJSValue.h"
>+#include "Error.h"
>+#include "JSCJSValueInlines.h"
>+//#include "JSCell.h"
>+#include "JSCellInlines.h"
>+#include "SlotVisitorInlines.h"
>+
>+#include "RuntimeType.h"
>+
>+namespace JSC {
>+
>+STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(ProxyObject);
>+
>+const ClassInfo ProxyObject::s_info = { "ProxyObject", &Base::s_info, 0, CREATE_METHOD_TABLE(ProxyObject) };
>+
>+ProxyObject::ProxyObject(VM& vm, Structure* structure)
>+    : Base(vm, structure)
>+{
>+}
>+
>+void ProxyObject::finishCreation(VM& vm, ExecState* exec, JSValue target, JSValue handler)
>+{
>+    UNUSED_PARAM(exec);
>+    Base::finishCreation(vm);
>+    if (!target.isObject()) {
>+        throwTypeError(exec, ASCIILiteral("A Proxy's 'target' should be an Object"));
>+        return;
>+    }
>+    if (ProxyObject* targetAsProxy = jsDynamicCast<ProxyObject*>(target)) {
>+        // FIXME: Add tests for this once we implement Proxy.revoke(.).
>+        if (targetAsProxy->handler().isNull()) {
>+            throwTypeError(exec, ASCIILiteral("If a Proxy's handler is another Proxy object, the other Proxy object must have a non-null handler."));
>+            return;
>+        }
>+    }
>+    if (!handler.isObject()) {
>+        throwTypeError(exec, ASCIILiteral("A Proxy's 'handler' should be an Object"));
>+        return;
>+    }
>+
>+    m_target.set(vm, this, jsCast<JSObject*>(target));
>+    m_handler.set(vm, this, handler);
>+}
>+
>+static EncodedJSValue performProxyGet(ExecState* exec, EncodedJSValue thisValue, PropertyName propertyName)
>+{
>+    VM& vm = exec->vm();
>+    JSObject* thisObject = jsCast<JSObject*>(JSValue::decode(thisValue)); // This might be a value where somewhere in __proto__ chain lives a ProxyObject.
>+    JSObject* proxyObjectAsObject = thisObject;
>+    // FIXME: make it so that custom getters take both the |this| value and the slotBase (property holder).
>+    while (true) {
>+        if (LIKELY(proxyObjectAsObject->inherits(ProxyObject::info())))
>+            break;
>+
>+        Structure& structure = *vm.heap.structureIDTable().get(proxyObjectAsObject->structureID());
>+        JSValue prototype = structure.storedPrototype();
>+        RELEASE_ASSERT(prototype.isObject());
>+        proxyObjectAsObject = asObject(prototype);
>+    }
>+
>+    ProxyObject* proxyObject = jsCast<ProxyObject*>(proxyObjectAsObject);
>+    JSValue handlerValue = proxyObject->handler();
>+    if (handlerValue.isNull())
>+        return throwVMTypeError(exec, ASCIILiteral("Proxy 'handler' is null. It should be an Object."));
>+
>+    JSObject* handler = jsCast<JSObject*>(handlerValue);
>+    JSObject* target = proxyObject->target();
>+    JSValue getHandler = handler->get(exec, vm.propertyNames->get);
>+    if (exec->hadException())
>+        return JSValue::encode(jsUndefined());
>+
>+    if (getHandler.isUndefined())
>+        return JSValue::encode(target->get(exec, propertyName));
>+
>+    if (!getHandler.isCell())
>+        return throwVMTypeError(exec, ASCIILiteral("'get' property of Proxy's handler should be callable."));
>+
>+    CallData callData;
>+    CallType callType = getHandler.asCell()->methodTable()->getCallData(getHandler.asCell(), callData);
>+    if (callType == CallTypeNone)
>+        return throwVMTypeError(exec, ASCIILiteral("'get' property of Proxy's handler should be callable."));
>+
>+    MarkedArgumentBuffer arguments;
>+    arguments.append(target);
>+    arguments.append(jsString(exec, propertyName.uid()));
>+    arguments.append(thisObject);
>+    JSValue trapResult = call(exec, getHandler, callType, callData, handler, arguments);
>+    if (exec->hadException())
>+        return JSValue::encode(jsUndefined());
>+
>+    PropertyDescriptor descriptor;
>+    if (target->getOwnPropertyDescriptor(exec, propertyName, descriptor)) {
>+        if (descriptor.isDataDescriptor() && !descriptor.configurable() && !descriptor.writable()) {
>+            if (!sameValue(exec, descriptor.value(), trapResult))
>+                return throwVMTypeError(exec, ASCIILiteral("Proxy handler's 'get' result of a non-configurable and non-writable property should be the same value as the target's property."));
>+        } else if (descriptor.isAccessorDescriptor() && !descriptor.configurable() && descriptor.getter().isUndefined()) {
>+            if (!trapResult.isUndefined())
>+                return throwVMTypeError(exec, ASCIILiteral("Proxy handler's 'get' result of a non-configurable accessor property without a getter should be undefined."));
>+        }
>+    }
>+
>+    // FIXME: when implementing Proxy.[[GetOwnProperty]] it would be a good test to
>+    // have handler be another Proxy where its handler throws on [[GetOwnProperty]]
>+    // right here.
>+    if (exec->hadException())
>+        return JSValue::encode(jsUndefined());
>+
>+    return JSValue::encode(trapResult);
>+}
>+
>+bool ProxyObject::getOwnPropertySlotCommon(ExecState*, PropertySlot& slot)
>+{
>+    if (slot.trapType() == PropertySlot::TrapType::Get) {
>+        slot.setCustom(this, CustomAccessor, performProxyGet);
>+        slot.disableCaching();
>+        return true;
>+    }
>+
>+    // FIXME: Implement other proxy traps.
>+    return false;
>+}
>+bool ProxyObject::getOwnPropertySlot(JSObject* object, ExecState* exec, PropertyName, PropertySlot& slot)
>+{
>+    ProxyObject* thisObject = jsCast<ProxyObject*>(object);
>+    return thisObject->getOwnPropertySlotCommon(exec, slot);
>+}
>+
>+bool ProxyObject::getOwnPropertySlotByIndex(JSObject* object, ExecState* exec, unsigned, PropertySlot& slot)
>+{
>+    ProxyObject* thisObject = jsCast<ProxyObject*>(object);
>+    return thisObject->getOwnPropertySlotCommon(exec, slot);
>+}
>+
>+void ProxyObject::visitChildren(JSCell* cell, SlotVisitor& visitor)
>+{
>+    ProxyObject* thisObject = jsCast<ProxyObject*>(cell);
>+    ASSERT_GC_OBJECT_INHERITS(thisObject, info());
>+    Base::visitChildren(thisObject, visitor);
>+
>+    visitor.append(&thisObject->m_target);
>+    visitor.append(&thisObject->m_handler);
>+}
>+
>+} // namespace JSC
>Index: Source/JavaScriptCore/runtime/ProxyObject.h
>===================================================================
>--- Source/JavaScriptCore/runtime/ProxyObject.h	(revision 0)
>+++ Source/JavaScriptCore/runtime/ProxyObject.h	(working copy)
>@@ -0,0 +1,74 @@
>+/*
>+ * Copyright (C) 2016 Apple Inc. All rights reserved.
>+ *
>+ * Redistribution and use in source and binary forms, with or without
>+ * modification, are permitted provided that the following conditions
>+ * are met:
>+ * 1. Redistributions of source code must retain the above copyright
>+ *    notice, this list of conditions and the following disclaimer.
>+ * 2. Redistributions in binary form must reproduce the above copyright
>+ *    notice, this list of conditions and the following disclaimer in the
>+ *    documentation and/or other materials provided with the distribution.
>+ *
>+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
>+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
>+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
>+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
>+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
>+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
>+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
>+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
>+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
>+ * THE POSSIBILITY OF SUCH DAMAGE.
>+ */
>+
>+#ifndef ProxyObject_h
>+#define ProxyObject_h
>+
>+#include "JSGlobalObject.h"
>+#include "JSObject.h"
>+
>+namespace JSC {
>+
>+class ProxyObject : public JSNonFinalObject {
>+public:
>+    typedef JSNonFinalObject Base;
>+
>+    const static unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot;
>+
>+    static ProxyObject* create(ExecState* exec, Structure* structure, JSValue target, JSValue handler)
>+    {
>+        VM& vm = exec->vm();
>+        ProxyObject* proxy = new (NotNull, allocateCell<ProxyObject>(vm.heap)) ProxyObject(vm, structure);
>+        proxy->finishCreation(vm, exec, target, handler);
>+        return proxy;
>+    }
>+
>+    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
>+    {
>+        return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info()); 
>+    }
>+
>+    DECLARE_EXPORT_INFO;
>+
>+    JSObject* target() { return m_target.get(); }
>+    JSValue handler() { return m_handler.get(); }
>+
>+private:
>+    ProxyObject(VM&, Structure*);
>+    void finishCreation(VM&, ExecState*, JSValue target, JSValue handler);
>+
>+    static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
>+    static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
>+    static void visitChildren(JSCell*, SlotVisitor&);
>+
>+    bool getOwnPropertySlotCommon(ExecState*, PropertySlot&);
>+
>+    WriteBarrier<JSObject> m_target;
>+    WriteBarrier<Unknown> m_handler;
>+};
>+
>+} // namespace JSC
>+
>+#endif // JSPromise_h
>Index: Source/JavaScriptCore/runtime/ReflectObject.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/ReflectObject.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/ReflectObject.cpp	(working copy)
>@@ -135,7 +135,7 @@ EncodedJSValue JSC_HOST_CALL reflectObje
>     if (exec->argumentCount() >= 3)
>         receiver = exec->argument(2);
> 
>-    PropertySlot slot(receiver);
>+    PropertySlot slot(receiver, PropertySlot::TrapType::Get);
>     return JSValue::encode(target.get(exec, propertyName, slot));
> }
> 
>Index: Source/JavaScriptCore/runtime/SamplingProfiler.cpp
>===================================================================
>--- Source/JavaScriptCore/runtime/SamplingProfiler.cpp	(revision 196582)
>+++ Source/JavaScriptCore/runtime/SamplingProfiler.cpp	(working copy)
>@@ -581,7 +581,7 @@ String SamplingProfiler::StackFrame::nam
> 
>     ExecState* exec = callee->globalObject()->globalExec();
>     auto getPropertyIfPureOperation = [&] (const Identifier& ident) -> String {
>-        PropertySlot slot(callee);
>+        PropertySlot slot(callee, PropertySlot::TrapType::VMInquiry);
>         PropertyName propertyName(ident);
>         if (callee->getPropertySlot(exec, propertyName, slot)) {
>             if (slot.isValue()) {
>Index: Source/JavaScriptCore/tests/es6.yaml
>===================================================================
>--- Source/JavaScriptCore/tests/es6.yaml	(revision 196582)
>+++ Source/JavaScriptCore/tests/es6.yaml	(working copy)
>@@ -913,7 +913,7 @@
> - path: es6/Proxy_construct_handler.js
>   cmd: runES6 :fail
> - path: es6/Proxy_constructor_requires_new.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_defineProperty_handler.js
>   cmd: runES6 :fail
> - path: es6/Proxy_deleteProperty_handler.js
>@@ -921,9 +921,9 @@
> - path: es6/Proxy_enumerate_handler.js
>   cmd: runES6 :fail
> - path: es6/Proxy_get_handler.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_get_handler_instances_of_proxies.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_getOwnPropertyDescriptor_handler.js
>   cmd: runES6 :fail
> - path: es6/Proxy_getPrototypeOf_handler.js
>@@ -953,27 +953,27 @@
> - path: es6/Proxy_internal_get_calls_Array.prototype.concat.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Array.prototype.pop.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_Array.prototype.reverse.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Array.prototype.shift.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_Array.prototype.splice.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Array.prototype.toString.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_Array.prototype_iteration_methods.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_ClassDefinitionEvaluation.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_CreateDynamicFunction.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_CreateListFromArrayLike.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_Date.prototype.toJSON.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Error.prototype.toString.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_Function.prototype.bind.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_HasBinding.js
>@@ -981,7 +981,7 @@
> - path: es6/Proxy_internal_get_calls_instanceof_operator.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_IteratorComplete_IteratorValue.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_JSON.stringify.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Object.assign.js
>@@ -989,7 +989,7 @@
> - path: es6/Proxy_internal_get_calls_Object.defineProperties.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_Promise_resolve_functions.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_RegExp.prototype.flags.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_RegExp.prototype.test.js
>@@ -1013,7 +1013,7 @@
> - path: es6/Proxy_internal_get_calls_String.prototype.split.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_String.raw.js
>-  cmd: runES6 :fail
>+  cmd: runES6 :normal
> - path: es6/Proxy_internal_get_calls_ToPrimitive.js
>   cmd: runES6 :fail
> - path: es6/Proxy_internal_get_calls_ToPropertyDescriptor.js
>@@ -1221,4 +1221,4 @@
> - path: es6/Object_static_methods_Object.getOwnPropertyDescriptors.js
>   cmd: runES6 :normal
> - path: es6/Object_static_methods_Object.getOwnPropertyDescriptors-proxy.js
>-  cmd: runES6 :fail
>\ No newline at end of file
>+  cmd: runES6 :fail
>Index: Source/JavaScriptCore/tests/stress/proxy-basic.js
>===================================================================
>--- Source/JavaScriptCore/tests/stress/proxy-basic.js	(revision 0)
>+++ Source/JavaScriptCore/tests/stress/proxy-basic.js	(working copy)
>@@ -0,0 +1,135 @@
>+function assert(b) {
>+    if (!b)
>+        throw new Error("Bad assertion");
>+}
>+
>+assert(Proxy instanceof Function);
>+assert(Proxy.length === 2);
>+assert(Proxy.prototype === undefined);
>+
>+{
>+    for (let i = 0; i < 1000; i++)
>+        assert((new Proxy({}, {})).__proto__ === Object.prototype);
>+}
>+
>+{
>+    // When we call Proxy it should throw
>+    for (let i = 0; i < 100; i++) {
>+        let threw = false;
>+        try {
>+            Proxy({}, {});
>+        } catch(e) {
>+            threw = true;
>+            assert(e.toString() === "TypeError: Proxy is not a function. (In 'Proxy({}, {})', 'Proxy' is an instance of Function)");
>+        }
>+        assert(threw === true);
>+    }
>+
>+    let theTarget = {
>+        x: 30
>+    };
>+
>+    let handler = {
>+        get: function(target, propName, proxyArg) {
>+            assert(target === theTarget);
>+            assert(proxyArg === proxy);
>+            if (propName === "y")
>+                return 45;
>+            assert(propName === "x");
>+            return target[propName];
>+        }
>+    };
>+
>+    let proxy = new Proxy(theTarget, handler);
>+    for (let i = 0; i < 1000; i++) {
>+        assert(proxy.x === 30);
>+        assert(proxy.y === 45);
>+        assert(proxy["x"] === 30);
>+        assert(proxy["y"] === 45);
>+    }
>+
>+}
>+
>+{
>+    let handler = {get: null};
>+    let target = {x: 20};
>+    let proxy = new Proxy(target, handler);
>+    for (let i = 0; i < 500; i++) {
>+        let threw = false;
>+        try {
>+            if (i % 2)
>+                proxy.foo;
>+            else
>+                proxy["foo"];
>+        } catch(e) {
>+            threw = true;
>+            assert(e.toString() === "TypeError: 'get' property of Proxy's handler should be callable.");
>+        }
>+        assert(threw);
>+    }
>+}
>+
>+{
>+    let handler = {get: {}};
>+    let target = {x: 20};
>+    let proxy = new Proxy(target, handler);
>+    for (let i = 0; i < 500; i++) {
>+        let threw = false;
>+        try {
>+            if (i % 2)
>+                proxy.foo;
>+            else
>+                proxy["foo"];
>+        } catch(e) {
>+            threw = true;
>+            assert(e.toString() === "TypeError: 'get' property of Proxy's handler should be callable.");
>+        }
>+        assert(threw);
>+    }
>+}
>+
>+{
>+    let handler = {};
>+    let target = {x: 20};
>+    let proxy = new Proxy(target, handler);
>+    for (let i = 0; i < 500; i++) {
>+        assert(proxy.x === 20);
>+        assert(proxy.y === undefined);
>+    }
>+}
>+
>+{
>+    let handler = {};
>+    let target = [1, 2, 3];
>+    let proxy = new Proxy(target, handler);
>+    for (let i = 0; i < 500; i++) {
>+        assert(proxy[0] === 1);
>+        assert(proxy[1] === 2);
>+        assert(proxy[2] === 3);
>+    }
>+}
>+
>+{
>+    let theTarget = [1, 2, 3];
>+    let handler = {
>+        get: function(target, propName, proxyArg) {
>+            switch (propName) {
>+            case "0":
>+            case "1":
>+                return 100;
>+            case "2":
>+            case "length":
>+                return target[propName];
>+            }
>+            assert(false);
>+        }
>+    };
>+    let proxy = new Proxy(theTarget, handler);
>+    for (let i = 0; i < 500; i++) {
>+        assert(proxy[0] === 100);
>+        assert(proxy[1] === 100);
>+        assert(proxy[2] === 3);
>+        assert(proxy.length === 3);
>+        assert(proxy["length"] === 3);
>+    }
>+}
>Index: Source/JavaScriptCore/tests/stress/proxy-in-proto-chain.js
>===================================================================
>--- Source/JavaScriptCore/tests/stress/proxy-in-proto-chain.js	(revision 0)
>+++ Source/JavaScriptCore/tests/stress/proxy-in-proto-chain.js	(working copy)
>@@ -0,0 +1,28 @@
>+function assert(b) {
>+    if (!b)
>+        throw new Error("Bad assertion");
>+}
>+
>+let theTarget = {
>+    x: 30
>+};
>+
>+let handler = {
>+    get: function(target, propName, proxyArg) {
>+        assert(target === theTarget);
>+        assert(proxyArg === obj);
>+        if (propName === "y")
>+            return 45;
>+        assert(propName === "x");
>+        return target[propName];
>+    }
>+};
>+
>+let proxy = new Proxy(theTarget, handler);
>+
>+let obj = Object.create(proxy);
>+
>+for (let i = 0; i < 1000; i++) {
>+    assert(obj.x === 30);
>+    assert(obj.y === 45);
>+}
>Index: Source/JavaScriptCore/tests/stress/proxy-property-descriptor.js
>===================================================================
>--- Source/JavaScriptCore/tests/stress/proxy-property-descriptor.js	(revision 0)
>+++ Source/JavaScriptCore/tests/stress/proxy-property-descriptor.js	(working copy)
>@@ -0,0 +1,83 @@
>+function assert(b) {
>+    if (!b)
>+        throw new Error("Bad assertion");
>+}
>+
>+let theTarget = {};
>+Object.defineProperty(theTarget, "x", {
>+    writable: false,
>+    configurable: false,
>+    value: 45
>+});
>+
>+Object.defineProperty(theTarget, "y", {
>+    writable: false,
>+    configurable: false,
>+    value: 45
>+});
>+
>+Object.defineProperty(theTarget, "getter", {
>+    configurable: false,
>+    set: function(x) { }
>+});
>+
>+Object.defineProperty(theTarget, "badGetter", {
>+    configurable: false,
>+    set: function(x) { }
>+});
>+
>+let handler = {
>+    get: function(target, propName, proxyArg) {
>+        assert(target === theTarget);
>+        assert(proxyArg === proxy);
>+        if (propName === "x")
>+            return 45;
>+        else if (propName === "y")
>+            return 30;
>+        else if (propName === "getter")
>+            return undefined;
>+        else {
>+            assert(propName === "badGetter");
>+            return 25;
>+        }
>+    }
>+};
>+
>+let proxy = new Proxy(theTarget, handler);
>+
>+for (let i = 0; i < 1000; i++) {
>+    assert(proxy.x === 45);
>+    assert(proxy["x"] === 45);
>+}
>+
>+for (let i = 0; i < 1000; i++) {
>+    try {
>+        if (i % 2)
>+            proxy.y;
>+        else
>+            proxy["y"];
>+    } catch(e) {
>+        threw = true;
>+        assert(e.toString() === "TypeError: Proxy handler's 'get' result of a non-configurable and non-writable property should be the same value as the target's property.");
>+    }
>+    assert(threw === true);
>+}
>+
>+for (let i = 0; i < 1000; i++) {
>+    assert(proxy.getter === undefined);
>+    assert(proxy["getter"] === undefined);
>+}
>+
>+for (let i = 0; i < 1000; i++) {
>+    try {
>+        if (i % 2)
>+            proxy.badGetter;
>+        else
>+            proxy["badGetter"];
>+
>+    } catch(e) {
>+        threw = true;
>+        assert(e.toString() === "TypeError: Proxy handler's 'get' result of a non-configurable accessor property without a getter should be undefined.");
>+    }
>+    assert(threw === true);
>+}
>Index: Source/JavaScriptCore/wasm/WASMModuleParser.cpp
>===================================================================
>--- Source/JavaScriptCore/wasm/WASMModuleParser.cpp	(revision 196582)
>+++ Source/JavaScriptCore/wasm/WASMModuleParser.cpp	(working copy)
>@@ -358,7 +358,7 @@ void WASMModuleParser::getImportedValue(
> {
>     FAIL_IF_FALSE(m_imports, "Accessing property of non-object.");
>     Identifier identifier = Identifier::fromString(&m_vm, importName);
>-    PropertySlot slot(m_imports.get());
>+    PropertySlot slot(m_imports.get(), PropertySlot::TrapType::Get);
>     if (!m_imports->getPropertySlot(exec, identifier, slot))
>         FAIL_WITH_MESSAGE("Can't find a property named \"" + importName + '"');
>     FAIL_IF_FALSE(slot.isValue(), "\"" + importName + "\" is not a data property.");
>Index: Source/WebCore/ChangeLog
>===================================================================
>--- Source/WebCore/ChangeLog	(revision 196582)
>+++ Source/WebCore/ChangeLog	(working copy)
>@@ -1,3 +1,32 @@
>+2016-02-15  Saam barati  <sbarati@apple.com>
>+
>+        Implement Proxy [[Get]]
>+        https://bugs.webkit.org/show_bug.cgi?id=154081
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        No new tests (OOPS!).
>+
>+        * bindings/js/JSCryptoAlgorithmDictionary.cpp:
>+        (WebCore::getProperty):
>+        (WebCore::getHashAlgorithm):
>+        * bindings/js/JSCryptoKeySerializationJWK.cpp:
>+        (WebCore::getJSArrayFromJSON):
>+        (WebCore::getStringFromJSON):
>+        (WebCore::getBooleanFromJSON):
>+        * bindings/js/JSDOMWindowCustom.cpp:
>+        (WebCore::DialogHandler::returnValue):
>+        * bindings/js/JSDictionary.cpp:
>+        (WebCore::JSDictionary::tryGetProperty):
>+        * bindings/js/JSStorageCustom.cpp:
>+        (WebCore::JSStorage::deleteProperty):
>+        (WebCore::JSStorage::deletePropertyByIndex):
>+        (WebCore::JSStorage::putDelegate):
>+        * bindings/js/SerializedScriptValue.cpp:
>+        (WebCore::CloneSerializer::getProperty):
>+        * testing/Internals.cpp:
>+        (WebCore::Internals::isReadableStreamDisturbed):
>+
> 2016-02-15  Daniel Bates  <dabates@apple.com>
> 
>         CSP: 'sandbox' should be ignored in report-only mode
>Index: Source/WebCore/bindings/js/JSCryptoAlgorithmDictionary.cpp
>===================================================================
>--- Source/WebCore/bindings/js/JSCryptoAlgorithmDictionary.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/JSCryptoAlgorithmDictionary.cpp	(working copy)
>@@ -95,7 +95,7 @@ bool JSCryptoAlgorithmDictionary::getAlg
> static JSValue getProperty(ExecState* exec, JSObject* object, const char* name)
> {
>     Identifier identifier = Identifier::fromString(exec, name);
>-    PropertySlot slot(object);
>+    PropertySlot slot(object, PropertySlot::TrapType::Get);
> 
>     if (object->getPropertySlot(exec, identifier, slot))
>         return slot.getValue(exec, identifier);
>@@ -111,7 +111,6 @@ static bool getHashAlgorithm(JSDictionar
>     JSObject* object = dictionary.initializerObject();
> 
>     Identifier identifier = Identifier::fromString(exec, "hash");
>-    PropertySlot slot(object);
> 
>     JSValue hash = getProperty(exec, object, "hash");
>     if (exec->hadException())
>Index: Source/WebCore/bindings/js/JSCryptoKeySerializationJWK.cpp
>===================================================================
>--- Source/WebCore/bindings/js/JSCryptoKeySerializationJWK.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/JSCryptoKeySerializationJWK.cpp	(working copy)
>@@ -53,7 +53,7 @@ namespace WebCore {
> static bool getJSArrayFromJSON(ExecState* exec, JSObject* json, const char* key, JSArray*& result)
> {
>     Identifier identifier = Identifier::fromString(exec, key);
>-    PropertySlot slot(json);
>+    PropertySlot slot(json, PropertySlot::TrapType::Get);
> 
>     if (!json->getPropertySlot(exec, identifier, slot))
>         return false;
>@@ -73,7 +73,7 @@ static bool getJSArrayFromJSON(ExecState
> static bool getStringFromJSON(ExecState* exec, JSObject* json, const char* key, String& result)
> {
>     Identifier identifier = Identifier::fromString(exec, key);
>-    PropertySlot slot(json);
>+    PropertySlot slot(json, PropertySlot::TrapType::Get);
> 
>     if (!json->getPropertySlot(exec, identifier, slot))
>         return false;
>@@ -94,7 +94,7 @@ static bool getStringFromJSON(ExecState*
> static bool getBooleanFromJSON(ExecState* exec, JSObject* json, const char* key, bool& result)
> {
>     Identifier identifier = Identifier::fromString(exec, key);
>-    PropertySlot slot(json);
>+    PropertySlot slot(json, PropertySlot::TrapType::Get);
> 
>     if (!json->getPropertySlot(exec, identifier, slot))
>         return false;
>Index: Source/WebCore/bindings/js/JSDOMWindowCustom.cpp
>===================================================================
>--- Source/WebCore/bindings/js/JSDOMWindowCustom.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/JSDOMWindowCustom.cpp	(working copy)
>@@ -641,7 +641,7 @@ inline JSValue DialogHandler::returnValu
>     if (!globalObject)
>         return jsUndefined();
>     Identifier identifier = Identifier::fromString(&m_exec, "returnValue");
>-    PropertySlot slot(globalObject);
>+    PropertySlot slot(globalObject, PropertySlot::TrapType::Get);
>     if (!JSGlobalObject::getOwnPropertySlot(globalObject, &m_exec, identifier, slot))
>         return jsUndefined();
>     return slot.getValue(&m_exec, identifier);
>Index: Source/WebCore/bindings/js/JSDictionary.cpp
>===================================================================
>--- Source/WebCore/bindings/js/JSDictionary.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/JSDictionary.cpp	(working copy)
>@@ -70,7 +70,7 @@ JSDictionary::GetPropertyResult JSDictio
> {
>     ASSERT(isValid());
>     Identifier identifier = Identifier::fromString(m_exec, propertyName);
>-    PropertySlot slot(m_initializerObject.get());
>+    PropertySlot slot(m_initializerObject.get(), PropertySlot::TrapType::Get);
> 
>     if (!m_initializerObject.get()->getPropertySlot(m_exec, identifier, slot))
>         return NoPropertyFound;
>Index: Source/WebCore/bindings/js/JSStorageCustom.cpp
>===================================================================
>--- Source/WebCore/bindings/js/JSStorageCustom.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/JSStorageCustom.cpp	(working copy)
>@@ -57,7 +57,7 @@ bool JSStorage::deleteProperty(JSCell* c
>     // Only perform the custom delete if the object doesn't have a native property by this name.
>     // Since hasProperty() would end up calling canGetItemsForName() and be fooled, we need to check
>     // the native property slots manually.
>-    PropertySlot slot(thisObject);
>+    PropertySlot slot(thisObject, PropertySlot::TrapType::GetOwnProperty);
> 
>     static_assert(!hasStaticPropertyTable, "This function does not handle static instance properties");
> 
>@@ -76,8 +76,6 @@ bool JSStorage::deleteProperty(JSCell* c
> 
> bool JSStorage::deletePropertyByIndex(JSCell* cell, ExecState* exec, unsigned propertyName)
> {
>-    JSStorage* thisObject = jsCast<JSStorage*>(cell);
>-    PropertySlot slot(thisObject);
>     static_assert(!hasStaticPropertyTable, "This function does not handle static instance properties");
>     return deleteProperty(cell, exec, Identifier::from(exec, propertyName));
> }
>@@ -105,7 +103,7 @@ bool JSStorage::putDelegate(ExecState* e
>     // Only perform the custom put if the object doesn't have a native property by this name.
>     // Since hasProperty() would end up calling canGetItemsForName() and be fooled, we need to check
>     // the native property slots manually.
>-    PropertySlot slot(this);
>+    PropertySlot slot(this, PropertySlot::TrapType::GetOwnProperty);
>     static_assert(!hasStaticPropertyTable, "This function does not handle static instance properties");
> 
>     JSValue prototype = this->prototype();
>Index: Source/WebCore/bindings/js/SerializedScriptValue.cpp
>===================================================================
>--- Source/WebCore/bindings/js/SerializedScriptValue.cpp	(revision 196582)
>+++ Source/WebCore/bindings/js/SerializedScriptValue.cpp	(working copy)
>@@ -641,7 +641,7 @@ private:
> 
>     JSValue getProperty(JSObject* object, const Identifier& propertyName)
>     {
>-        PropertySlot slot(object);
>+        PropertySlot slot(object, PropertySlot::TrapType::Get);
>         if (object->methodTable()->getOwnPropertySlot(object, m_exec, propertyName, slot))
>             return slot.getValue(m_exec, propertyName);
>         return JSValue();
>Index: Source/WebCore/testing/Internals.cpp
>===================================================================
>--- Source/WebCore/testing/Internals.cpp	(revision 196582)
>+++ Source/WebCore/testing/Internals.cpp	(working copy)
>@@ -3442,7 +3442,7 @@ bool Internals::isReadableStreamDisturbe
>     JSVMClientData* clientData = static_cast<JSVMClientData*>(state.vm().clientData);
>     const Identifier& privateName = clientData->builtinFunctions().readableStreamInternalsBuiltins().isReadableStreamDisturbedPrivateName();
>     JSValue value;
>-    PropertySlot propertySlot(value);
>+    PropertySlot propertySlot(value, PropertySlot::TrapType::Get);
>     globalObject->fastGetOwnPropertySlot(&state, state.vm(), *globalObject->structure(), privateName, propertySlot);
>     value = propertySlot.getValue(&state, privateName);
>     ASSERT(value.isFunction());

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Attachments on bug 154081: 271313 | 271397 | 271444 | 271448 | 271454 | 271473 | 271493 | 271507 | 271518