IDL: Add PropertyBag class

Source/bindings/core/v8/v8.gypi

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
     'includes': [
         'custom/custom.gypi',
         '../../modules/v8/generated.gypi',
     ],
     'variables': {
@@ skipping 31 matching lines @@
             'ModuleProxy.cpp',
             'ModuleProxy.h',
             'NPV8Object.cpp',
             'NPV8Object.h',
             'Nullable.h',
             'PageScriptDebugServer.cpp',
             'PageScriptDebugServer.h',
             'PostMessage.h',
             'PrivateScriptRunner.cpp',
             'PrivateScriptRunner.h',
+            'PropertyBag.cpp',
+            'PropertyBag.h',
             'RetainedDOMInfo.cpp',
             'RetainedDOMInfo.h',
             'RetainedObjectInfo.h',
             'ScheduledAction.cpp',
             'ScheduledAction.h',
             'ScopedPersistent.h',
             'ScriptCallStackFactory.cpp',
             'ScriptCallStackFactory.h',
             'ScriptController.cpp',
             'ScriptController.h',
@@ skipping 103 matching lines @@
         ],
         'bindings_core_v8_unittest_files': [
             'ScriptPromiseResolverTest.cpp',
             'ScriptPromiseTest.cpp',
             'ScriptPromisePropertyTest.cpp',
             'SerializedScriptValueTest.cpp',
             'V8BindingTest.cpp',
         ],
     },
 }