Oilpan: Remove unnecessary trace methods in the supplement hierarchy.

Source/core/html/imports/HTMLImportsController.h

 /*
  * 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 60 matching lines @@
     HTMLImportChild* load(HTMLImport* parent, HTMLImportChildClient*, FetchRequest);
     void showSecurityErrorMessage(const String&);
 
     SecurityOrigin* securityOrigin() const;
     ResourceFetcher* fetcher() const;
     LocalFrame* frame() const;
     Document* master() const { return m_master; }
 
     void recalcTimerFired(Timer<HTMLImportsController>*);
 
-    virtual void trace(Visitor* visitor) OVERRIDE { DocumentSupplement::trace(visitor); }
-
     HTMLImportLoader* createLoader();
 
     size_t loaderCount() const { return m_loaders.size(); }
     HTMLImportLoader* loaderAt(size_t i) const { return m_loaders[i].get(); }
     HTMLImportLoader* loaderFor(const Document&) const;
 
     void scheduleRecalcState();
     HTMLImportChild* findLinkFor(const KURL&, HTMLImport* excluding = 0) const;
 
 private:
     HTMLImportChild* createChild(const KURL&, HTMLImport* parent, HTMLImportChildClient*);
     void clear();
 
     Document* m_master;
     Timer<HTMLImportsController> m_recalcTimer;
 
     // List of import which has been loaded or being loaded.
     typedef Vector<OwnPtr<HTMLImportChild> > ImportList;
     ImportList m_imports;
 
     typedef Vector<RefPtr<HTMLImportLoader> > LoaderList;
     LoaderList m_loaders;
 };
 
 DEFINE_TYPE_CASTS(HTMLImportsController, HTMLImport, import, import->isRoot(), import.isRoot());
 
 } // namespace WebCore
 
 #endif // HTMLImportsController_h