Remove duplicated headers from core/

Source/core/dom/MutationObserver.cpp

 /*
  * Copyright (C) 2011 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 23 matching lines @@
 #include <algorithm>
 #include "bindings/v8/Dictionary.h"
 #include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/MutationCallback.h"
 #include "core/dom/MutationObserverRegistration.h"
 #include "core/dom/MutationRecord.h"
 #include "core/dom/Node.h"
-#include "wtf/HashSet.h"
 #include "wtf/MainThread.h"
-#include "wtf/Vector.h"
 
 namespace WebCore {
 
 static unsigned s_observerPriority = 0;
 
 struct MutationObserver::ObserverLessThan {
     bool operator()(const RefPtr<MutationObserver>& lhs, const RefPtr<MutationObserver>& rhs)
     {
         return lhs->m_priority < rhs->m_priority;
     }
@@ skipping 202 matching lines @@
                 observers[i]->deliver();
             else
                 suspendedMutationObservers().add(observers[i]);
         }
     }
 
     deliveryInProgress = false;
 }
 
 } // namespace WebCore