Prevent 'removetrack' events from firing when all inband text tracks are removed.

Source/core/html/track/InbandTextTrack.cpp

 /*
  * Copyright (C) 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 66 matching lines @@
     // Make sure m_webTrack was cleared by trackRemoved() before destruction.
     ASSERT(!m_webTrack);
 }
 
 size_t InbandTextTrack::inbandTrackIndex()
 {
     ASSERT(m_webTrack);
     return m_webTrack->textTrackIndex();
 }
 
-void InbandTextTrack::trackRemoved()
+void InbandTextTrack::setTrackList(TextTrackList* trackList)
 {
+    TextTrack::setTrackList(trackList);
+    if (trackList)
+        return;
+
     ASSERT(m_webTrack);
     m_webTrack->setClient(0);
     m_webTrack = 0;
     clearClient();
 }
 
 void InbandTextTrack::addWebVTTCue(double start, double end, const WebString& id, const WebString& content, const WebString& settings)
 {
     RefPtr<VTTCue> cue = VTTCue::create(document(), start, end, content);
     cue->setId(id);
     cue->parseSettings(settings);
     addCue(cue);
 }
 
 } // namespace WebCore