Oilpan: Allocate all EventTarget derived types on the manged heap.

Source/core/html/track/TextTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2011, 2012, 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 427 matching lines @@
 {
     return mediaElement();
 }
 
 void TextTrack::trace(Visitor* visitor)
 {
     visitor->trace(m_cues);
     visitor->trace(m_regions);
     visitor->trace(m_trackList);
     TrackBase::trace(visitor);
+    EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore