Sync CSS interfaces with the specs

Source/core/css/StyleSheetList.idl

Index: Source/core/css/StyleSheetList.idl
diff --git a/Source/core/css/StyleSheetList.idl b/Source/core/css/StyleSheetList.idl
index 3da2d91e544bb51fdd689a12863a6d871945191a..85d4c4478969e1a3fca7e3c14ef23642651a8431 100644
--- a/Source/core/css/StyleSheetList.idl
+++ b/Source/core/css/StyleSheetList.idl
@@ -18,12 +18,16 @@
  * Boston, MA 02110-1301, USA.
  */
 
-// Introduced in DOM Level 2:
+// http://dev.w3.org/csswg/cssom/#the-stylesheetlist-interface
+
+// TODO(philipj): StyleSheetList should be an [ArrayClass].
 [
     SetWrapperReferenceFrom=document,
     WillBeGarbageCollected
 ] interface StyleSheetList {
+    getter StyleSheet? item(unsigned long index);
     readonly attribute unsigned long length;
-    getter StyleSheet item(unsigned long index);
+
+    // Non-standard APIs
     [NotEnumerable] getter CSSStyleSheet (DOMString name);
 };