Add support for [TreatNullAs] extended attribute for reflected attributes

Source/core/dom/Element.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 43 matching lines @@
     [RaisesException, CustomElementCallbacks] Attr setAttributeNodeNS([Default=Undefined, StrictTypeChecking] optional Attr newAttr);
     boolean hasAttribute(DOMString name);
      boolean hasAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                           [Default=Undefined] optional DOMString localName);
 
     [PerWorldBindings] readonly attribute CSSStyleDeclaration style;
 
     // DOM4
     // iht.com relies on id returning the empty string when no id is present.
     // Other browsers do this as well. So we don't convert null to JS null.
-    [Reflect] attribute DOMString id;
+    [Reflect, TreatNullAs=NullString] attribute DOMString id;
     [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString namespaceURI;
     [TreatReturnedNullStringAs=Null, TreatNullAs=NullString, PerWorldBindings, SetterRaisesException] attribute DOMString prefix;
     [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString localName;
 
     // Common extensions
 
     [PerWorldBindings] readonly attribute long offsetLeft;
     [PerWorldBindings] readonly attribute long offsetTop;
     [PerWorldBindings] readonly attribute long offsetWidth;
     [PerWorldBindings] readonly attribute long offsetHeight;
@@ skipping 13 matching lines @@
 
     // WebKit extensions
 
     void scrollIntoViewIfNeeded(optional boolean centerIfNeeded);
     void scrollByLines([Default=Undefined] optional long lines);
     void scrollByPages([Default=Undefined] optional long pages);
 
     // HTML 5
     NodeList getElementsByClassName([Default=Undefined] optional DOMString name);
 
-    [Reflect=class, PerWorldBindings] attribute DOMString className;
+    [Reflect=class, TreatNullAs=NullString, PerWorldBindings] attribute DOMString className;
     [PerWorldBindings] readonly attribute DOMTokenList classList;
 
     [PerWorldBindings] readonly attribute DOMStringMap dataset;
 
     // NodeSelector - Selector API
     [RaisesException] Element querySelector(DOMString selectors);
     [RaisesException] NodeList querySelectorAll(DOMString selectors);
 
     // WebKit extension, pending specification.
     [RaisesException] boolean webkitMatchesSelector([Default=Undefined] optional DOMString selectors);
 
     // Shadow DOM API
-    [EnabledAtRuntime=ShadowDOM, Reflect, PerWorldBindings] attribute DOMString pseudo;
+    [EnabledAtRuntime=ShadowDOM, Reflect, TreatNullAs=NullString, PerWorldBindings] attribute DOMString pseudo;
     [EnabledAtRuntime=ShadowDOM, RaisesException] ShadowRoot createShadowRoot();
     [EnabledAtRuntime=ShadowDOM, PerWorldBindings] readonly attribute ShadowRoot shadowRoot;
     [EnabledAtRuntime=ShadowDOM, PerWorldBindings] NodeList getDestinationInsertionPoints();
 
     // To-be-deprecated prefixed Shadow DOM API
-    [Reflect=pseudo, ImplementedAs=pseudo, PerWorldBindings, MeasureAs=ShadowDOMPrefixedPseudo] attribute DOMString webkitPseudo;
+    [Reflect=pseudo, TreatNullAs=NullString, ImplementedAs=pseudo, PerWorldBindings, MeasureAs=ShadowDOMPrefixedPseudo] attribute DOMString webkitPseudo;
     [ImplementedAs=createShadowRoot, RaisesException, MeasureAs=ShadowDOMPrefixedCreateShadowRoot] ShadowRoot webkitCreateShadowRoot();
     [ImplementedAs=shadowRoot, PerWorldBindings, MeasureAs=ShadowDOMPrefixedShadowRoot] readonly attribute ShadowRoot webkitShadowRoot;
 
     // CSSOM View Module API
     ClientRectList getClientRects();
     ClientRect getBoundingClientRect();
 
     // Mozilla version
     const unsigned short ALLOW_KEYBOARD_INPUT = 1;
     [EnabledAtRuntime=Fullscreen, PerWorldBindings, ActivityLog=Access] void webkitRequestFullScreen([Default=Undefined] optional unsigned short flags);
@@ skipping 78 matching lines @@
     [NotEnumerable, EnabledAtRuntime=Touch, PerWorldBindings] attribute EventHandler ontouchstart;
     [NotEnumerable, EnabledAtRuntime=Touch, PerWorldBindings] attribute EventHandler ontouchmove;
     [NotEnumerable, EnabledAtRuntime=Touch, PerWorldBindings] attribute EventHandler ontouchend;
     [NotEnumerable, EnabledAtRuntime=Touch, PerWorldBindings] attribute EventHandler ontouchcancel;
     [NotEnumerable, PerWorldBindings] attribute EventHandler onwebkitfullscreenchange;
     [NotEnumerable, PerWorldBindings] attribute EventHandler onwebkitfullscreenerror;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;