Oilpan: make Supplementable tracing more regular.

Source/core/workers/SharedWorker.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 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 85 matching lines @@
     return EventTargetNames::SharedWorker;
 }
 
 bool SharedWorker::hasPendingActivity() const
 {
     return m_isBeingConnected;
 }
 
 void SharedWorker::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_port);
+    HeapSupplementable<SharedWorker>::trace(visitor);
+#endif
     AbstractWorker::trace(visitor);
-    WillBeHeapSupplementable<SharedWorker>::trace(visitor);
 }
 
 } // namespace blink