Oilpan: Remove support for tracing off-heap HashSets.

Source/core/fileapi/FileReader.cpp

 /*
  * Copyright (C) 2010 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 131 matching lines @@
     void finishReader(FileReader* reader, FinishReaderType nextStep)
     {
         if (nextStep == RunPendingReaders)
             executeReaders();
     }
 
     void trace(Visitor* visitor)
     {
 #if ENABLE(OILPAN)
         visitor->trace(m_pendingReaders);
+        visitor->trace(m_runningReaders);
 #endif
-        visitor->trace(m_runningReaders);
         WillBeHeapSupplement<LocalFrame>::trace(visitor);
         WillBeHeapSupplement<WorkerClients>::trace(visitor);
     }
 
 private:
     ThrottlingController()
         : m_maxRunningReaders(kMaxOutstandingRequestsPerThread)
     {
     }
 
@@ skipping 291 matching lines @@
     return m_loader->stringResult();
 }
 
 void FileReader::trace(Visitor* visitor)
 {
     visitor->trace(m_error);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace WebCore