InlinedVisitor: Migrate html to use inlined tracing

Source/core/html/track/vtt/VTTRegion.cpp

 /*
  * Copyright (C) 2013 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 451 matching lines @@
 }
 
 void VTTRegion::scrollTimerFired(Timer<VTTRegion>*)
 {
     WTF_LOG(Media, "VTTRegion::scrollTimerFired");
 
     stopTimer();
     displayLastVTTCueBox();
 }
 
-void VTTRegion::trace(Visitor* visitor)
+DEFINE_TRACE(VTTRegion)
 {
     visitor->trace(m_cueContainer);
     visitor->trace(m_regionDisplayTree);
     visitor->trace(m_track);
 }
 
 } // namespace blink