Support for CSSOM CSSNamespaceRule interface

Source/core/css/CSSRule.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 14 matching lines @@
     WillBeGarbageCollected,
 ] interface CSSRule {
     const unsigned short STYLE_RULE = 1;
     const unsigned short CHARSET_RULE = 2;
     const unsigned short IMPORT_RULE = 3;
     const unsigned short MEDIA_RULE = 4;
     const unsigned short FONT_FACE_RULE = 5;
     const unsigned short PAGE_RULE = 6;
     // TODO(philipj): Implement CSSMarginRule.
     // const unsigned short MARGIN_RULE = 9;
-    // TODO(philipj): Implement CSSNamespaceRule. crbug.com/389549
-    // const unsigned short NAMESPACE_RULE = 10;
+    const unsigned short NAMESPACE_RULE = 10;
     readonly attribute unsigned short type;
     attribute DOMString cssText;
     readonly attribute CSSRule? parentRule;
     readonly attribute CSSStyleSheet? parentStyleSheet;
 
     // CSS Animations
     // http://dev.w3.org/csswg/css-animations/#interface-cssrule
     const unsigned short KEYFRAMES_RULE = 7;
     const unsigned short KEYFRAME_RULE = 8;
 
     // CSS Conditional Rules
     // http://dev.w3.org/csswg/css-conditional/#extentions-to-cssrule-interface
     const unsigned short SUPPORTS_RULE = 12;
 
     // CSS Device Adaptation
     // http://dev.w3.org/csswg/css-device-adapt/#css-rule-interface
     [RuntimeEnabled=CSSViewport] const unsigned short VIEWPORT_RULE = 15;
 
     // Non-standard APIs
     const unsigned short WEBKIT_KEYFRAMES_RULE = 7;
     const unsigned short WEBKIT_KEYFRAME_RULE = 8;
 };