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

Source/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 1539 matching lines @@
 {
     for (unsigned i = 0; i < m_viewportDependentMediaQueryResults.size(); ++i) {
         if (m_medium->eval(m_viewportDependentMediaQueryResults[i]->expression()) != m_viewportDependentMediaQueryResults[i]->result())
             return true;
     }
     return false;
 }
 
 void StyleResolver::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_keyframesRuleMap);
     visitor->trace(m_matchedPropertiesCache);
     visitor->trace(m_viewportDependentMediaQueryResults);
     visitor->trace(m_viewportStyleResolver);
     visitor->trace(m_features);
     visitor->trace(m_siblingRuleSet);
     visitor->trace(m_uncommonAttributeRuleSet);
     visitor->trace(m_watchedSelectorsRules);
     visitor->trace(m_treeBoundaryCrossingRules);
     visitor->trace(m_pendingStyleSheets);
+#endif
 }
 
 } // namespace WebCore