Oilpan: make Supplementable tracing more regular.

Source/core/clipboard/DataObject.cpp

 /*
  * Copyright (c) 2008, 2009, 2012 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 241 matching lines @@
 }
 
 void DataObject::internalAddFileItem(PassRefPtrWillBeRawPtr<DataObjectItem> item)
 {
     ASSERT(item->kind() == DataObjectItem::FileKind);
     m_itemList.append(item);
 }
 
 void DataObject::trace(Visitor* visitor)
 {
+#if ENABLE(OILPAN)
     visitor->trace(m_itemList);
-    WillBeHeapSupplementable<DataObject>::trace(visitor);
+    HeapSupplementable<DataObject>::trace(visitor);
+#endif
 }
 
 } // namespace blink