Make text track and cue wrapper objects dependent on their media element.

Source/core/html/track/TextTrack.idl

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
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 enum TextTrackMode { "disabled",  "hidden",  "showing" };
 enum TextTrackKind { "subtitles",  "captions",  "descriptions",  "chapters",  "metadata" };
 
-interface TextTrack : EventTarget {
+[
+    SetWrapperReferenceFrom=owner,
+] interface TextTrack : EventTarget {
     readonly attribute TextTrackKind kind;
     readonly attribute DOMString label;
     readonly attribute DOMString language;
 
     readonly attribute DOMString id;
 
              attribute TextTrackMode mode;
 
     readonly attribute TextTrackCueList cues;
     readonly attribute TextTrackCueList activeCues;
 
     void addCue(TextTrackCue cue);
     [RaisesException] void removeCue(TextTrackCue cue);
 
              attribute EventHandler oncuechange;
 
     [RuntimeEnabled=WebVTTRegions] readonly attribute VTTRegionList regions;
     [RuntimeEnabled=WebVTTRegions] void addRegion(VTTRegion region);
     [RaisesException, RuntimeEnabled=WebVTTRegions] void removeRegion(VTTRegion region);
 };