Revert of Enable per thread heap for database thread

third_party/WebKit/Source/modules/webdatabase/DatabaseThread.h

 /*
  * Copyright (C) 2007, 2008 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 59 matching lines @@
 
     void setupDatabaseThread();
     void cleanupDatabaseThread();
     void cleanupDatabaseThreadCompleted();
 
     OwnPtr<WebThreadSupportingGC> m_thread;
 
     // This set keeps track of the open databases that have been used on this thread.
     // This must be updated in the database thread though it is constructed and
     // destructed in the context thread.
-    HashSet<CrossThreadPersistent<Database>> m_openDatabaseSet;
+    HeapHashSet<Member<Database>> m_openDatabaseSet;
 
     OwnPtr<SQLTransactionClient> m_transactionClient;
-    CrossThreadPersistent<SQLTransactionCoordinator> m_transactionCoordinator;
+    Member<SQLTransactionCoordinator> m_transactionCoordinator;
     TaskSynchronizer* m_cleanupSync;
 
     Mutex m_terminationRequestedMutex;
     bool m_terminationRequested;
 };
 
 } // namespace blink
 
 #endif // DatabaseThread_h