Sync CSS interfaces with the specs

Source/core/css/CSSStyleSheet.idl

 /*
  * Copyright (C) 2006, 2007, 2008 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
-// Introduced in DOM Level 2:
+// http://dev.w3.org/csswg/cssom/#the-cssstylesheet-interface
+
 [
     SetWrapperReferenceFrom=ownerNode,
 ] interface CSSStyleSheet : StyleSheet {
-    readonly attribute CSSRule          ownerRule;
-    readonly attribute CSSRuleList      cssRules;
-
+    readonly attribute CSSRule? ownerRule;
+    [SameObject] readonly attribute CSSRuleList cssRules;
+    // TODO(philipj): The index argument should not be optional. crbug.com/319695
     [RaisesException] unsigned long insertRule(DOMString rule, optional unsigned long index);
     [RaisesException] void deleteRule(unsigned long index);
 
-    // IE Extensions
+    // Non-standard APIs
     [MeasureAs=CSSStyleSheetRules] readonly attribute CSSRuleList rules;
-
-    [RaisesException, MeasureAs=CSSStyleSheetAddRule] long addRule([Default=Undefined] optional DOMString selector,
-                                                                   [Default=Undefined] optional DOMString style,
-                                                                   optional unsigned long index);
-    [RaisesException, MeasureAs=CSSStyleSheetRemoveRule] void removeRule([Default=Undefined] optional unsigned long index);
+    [MeasureAs=CSSStyleSheetAddRule, RaisesException] long addRule([Default=Undefined] optional DOMString selector, [Default=Undefined] optional DOMString style, optional unsigned long index);
+    [MeasureAs=CSSStyleSheetRemoveRule, RaisesException] void removeRule([Default=Undefined] optional unsigned long index);
 };