Oilpan: Remove support for tracing of off-heap ListHashSets.

Source/core/css/MediaQueryList.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 96 matching lines @@
 }
 
 bool MediaQueryList::matches()
 {
     updateMatches();
     return m_matches;
 }
 
 void MediaQueryList::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_matcher);
     visitor->trace(m_media);
     visitor->trace(m_listeners);
+#endif
 }
 
 }