Add support for DOM4's XMLDocument interface

Source/core/frame/Window.idl

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google 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
@@ skipping 177 matching lines @@
     attribute EventHandler onwebkitanimationstart;
     attribute EventHandler onwebkittransitionend;
     [PerWorldBindings, ActivityLogging=SetterForIsolatedWorlds] attribute EventHandler onwheel;
 
     [DeprecateAs=CaptureEvents] void captureEvents();
     [DeprecateAs=ReleaseEvents] void releaseEvents();
 
     // Additional constructors.
     attribute TransitionEventConstructor WebKitTransitionEvent;
     [RuntimeEnabled=CSSAnimationUnprefixed] attribute WebKitAnimationEventConstructor AnimationEvent;
-    // Mozilla has a separate XMLDocument object for XML documents.
-    // We just use Document for this.
-    attribute DocumentConstructor XMLDocument;
     attribute URLConstructor webkitURL; // FIXME: deprecate this.
     attribute MutationObserverConstructor WebKitMutationObserver; // FIXME: Add metrics to determine when we can remove this.
     attribute IDBCursorConstructor webkitIDBCursor;
     attribute IDBDatabaseConstructor webkitIDBDatabase;
     attribute IDBFactoryConstructor webkitIDBFactory;
     attribute IDBIndexConstructor webkitIDBIndex;
     attribute IDBKeyRangeConstructor webkitIDBKeyRange;
     attribute IDBObjectStoreConstructor webkitIDBObjectStore;
     attribute IDBRequestConstructor webkitIDBRequest;
     attribute IDBTransactionConstructor webkitIDBTransaction;
@@ skipping 24 matching lines @@
     [ImplementedAs=anonymousIndexedGetter, NotEnumerable] getter Window(unsigned long index);
     [Custom, NotEnumerable] getter Window (DOMString name);
 };
 
 Window implements GlobalEventHandlers;
 Window implements ImageBitmapFactories;
 Window implements WindowBase64;
 Window implements WindowEventHandlers;
 Window implements WindowTimers;