Update WebKit IDLs after chrome roll.

html/track/TextTrackList.idl

 /*
  * Copyright (C) 2011 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
 [
     Conditional=VIDEO_TRACK,
     V8EnabledAtRuntime=webkitVideoTrack,
     IndexedGetter,
     EventTarget,
-    JSCustomMarkFunction,
-    JSCustomIsReachable,
     V8GenerateIsReachable=ImplOwnerRoot
 ] interface TextTrackList {
     readonly attribute unsigned long length;
     TextTrack item(in unsigned long index);
 
     attribute EventListener onaddtrack;
 
     void addEventListener(in DOMString type,
                           in EventListener listener,
                           in [Optional] boolean useCapture);
     void removeEventListener(in DOMString type,
                              in EventListener listener,
                              in [Optional] boolean useCapture);
     boolean dispatchEvent(in Event evt)
         raises(EventException);
 };