Clean up forward declarations in Source/modules

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 23 matching lines @@
 #include "wtf/HashMap.h"
 #include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
 
 class Database;
 class DatabaseTask;
-class Document;
-class MessageLoopInterruptor;
-class PendingGCRunner;
 class SQLTransactionClient;
 class SQLTransactionCoordinator;
 class TaskSynchronizer;
 
 class DatabaseThread : public GarbageCollectedFinalized<DatabaseThread> {
 public:
     static DatabaseThread* create() { return new DatabaseThread; }
     ~DatabaseThread();
     void trace(Visitor*);
 
@@ skipping 30 matching lines @@
     Member<SQLTransactionCoordinator> m_transactionCoordinator;
     TaskSynchronizer* m_cleanupSync;
 
     mutable Mutex m_terminationRequestedMutex;
     bool m_terminationRequested;
 };
 
 } // namespace blink
 
 #endif // DatabaseThread_h