Move id attribute to parent Element interface

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 41 matching lines @@
                                                    [Default=Undefined] optional DOMString localName);
      Attr getAttributeNodeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                            [Default=Undefined] optional DOMString localName);
     [RaisesException] 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;
+
     // Common extensions
 
     [PerWorldBindings] readonly attribute long offsetLeft;
     [PerWorldBindings] readonly attribute long offsetTop;
     [PerWorldBindings] readonly attribute long offsetWidth;
     [PerWorldBindings] readonly attribute long offsetHeight;
     [ImplementedAs=bindingsOffsetParent, PerWorldBindings] readonly attribute Element offsetParent;
     [PerWorldBindings] readonly attribute long clientLeft;
     [PerWorldBindings] readonly attribute long clientTop;
     [PerWorldBindings] readonly attribute long clientWidth;
@@ skipping 126 matching lines @@
     [NotEnumerable, EnabledAtRuntime=touch, PerWorldBindings] attribute EventListener ontouchmove;
     [NotEnumerable, EnabledAtRuntime=touch, PerWorldBindings] attribute EventListener ontouchend;
     [NotEnumerable, EnabledAtRuntime=touch, PerWorldBindings] attribute EventListener ontouchcancel;
     [NotEnumerable, PerWorldBindings] attribute EventListener onwebkitfullscreenchange;
     [NotEnumerable, PerWorldBindings] attribute EventListener onwebkitfullscreenerror;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;