Sync CSS interfaces with the specs

Source/core/css/CSSSupportsRule.idl

 /* Copyright (C) 2012 Motorola Mobility Inc. All rights reserved.
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+// http://dev.w3.org/csswg/css-conditional/#the-csssupportsrule-interface
+
+// TODO(philipj): CSSSupportsRule should inherit from CSSConditionRule and
+// inherit all members.
 interface CSSSupportsRule : CSSRule {
-    readonly attribute CSSRuleList cssRules;
+    // http://dev.w3.org/csswg/css-conditional/#the-cssconditionrule-interface
     readonly attribute DOMString conditionText;
-
+    // http://dev.w3.org/csswg/cssom/#the-cssgroupingrule-interface
+    [SameObject] readonly attribute CSSRuleList cssRules;
     [RaisesException] unsigned long insertRule(DOMString rule, unsigned long index);
     [RaisesException] void deleteRule(unsigned long index);
 };