Implement DataCue interface.

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 82 matching lines @@
     ASSERT(m_webTrack);
     m_webTrack->setClient(0);
     m_webTrack = 0;
 }
 
 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);
+    addCue(cue, ASSERT_NO_EXCEPTION);
 }
 
 } // namespace WebCore