Remove TextTrackClient interface to simplify TextTrack code.

Source/core/html/track/TextTrackList.cpp

 /*
  * Copyright (C) 2011, 2012 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 244 matching lines @@
 {
     return EventTargetNames::TextTrackList;
 }
 
 ExecutionContext* TextTrackList::executionContext() const
 {
     ASSERT(m_owner);
     return m_owner->executionContext();
 }
 
-void TextTrackList::clearOwnerAndClients()
+void TextTrackList::clearOwner()
 {
     m_owner = 0;
 
     for (unsigned i = 0; i < length(); ++i)
-        item(i)->clearClient();
+        item(i)->setTrackList(0);
 }
 
 void TextTrackList::scheduleTrackEvent(const AtomicString& eventName, PassRefPtr<TextTrack> track)
 {
     TrackEventInit initializer;
     initializer.track = track;
     initializer.bubbles = false;
     initializer.cancelable = false;
 
     m_asyncEventQueue->enqueueEvent(TrackEvent::create(eventName, initializer));
@@ skipping 38 matching lines @@
     // interface, with the track attribute initialized to the text track's
     // TextTrack object, at the media element's textTracks attribute's
     // TextTrackList object.
     scheduleTrackEvent(EventTypeNames::removetrack, track);
 }
 
 HTMLMediaElement* TextTrackList::owner() const
 {
     return m_owner;
 }