Clean up forward declarations in Source/core/events

Source/core/events/EventListener.h

 /*
  * Copyright (C) 2006, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef EventListener_h
 #define EventListener_h
 
 #include "wtf/RefCounted.h"
 
 namespace blink {
 
-    class DOMWrapperWorld;
     class Event;
     class ExecutionContext;
 
     class EventListener : public RefCounted<EventListener> {
     public:
         enum Type {
             JSEventListenerType,
             ImageEventListenerType,
             CPPEventListenerType,
             ConditionEventListenerType,
@@ skipping 17 matching lines @@
 
     private:
         virtual bool virtualisAttribute() const { return false; }
 
         Type m_type;
     };
 
 }
 
 #endif