Don't expose the user agent shadow tree

Source/core/events/Event.h

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 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.
@@ skipping 96 matching lines @@
     virtual ~Event();
 
     void initEvent(const AtomicString& type, bool canBubble, bool cancelable);
 
     const AtomicString& type() const { return m_type; }
     void setType(const AtomicString& type) { m_type = type; }
 
     EventTarget* target() const { return m_target.get(); }
     void setTarget(PassRefPtrWillBeRawPtr<EventTarget>);
 
-    EventTarget* currentTarget() const { return m_currentTarget; }
+    EventTarget* currentTarget() const;
     void setCurrentTarget(EventTarget* currentTarget) { m_currentTarget = currentTarget; }
 
     unsigned short eventPhase() const { return m_eventPhase; }
     void setEventPhase(unsigned short eventPhase) { m_eventPhase = eventPhase; }
 
     bool bubbles() const { return m_canBubble; }
     bool cancelable() const { return m_cancelable; }
     DOMTimeStamp timeStamp() const { return m_createTime; }
 
     void stopPropagation() { m_propagationStopped = true; }
@@ skipping 81 matching lines @@
     RefPtrWillBeMember<Event> m_underlyingEvent;
     OwnPtrWillBeMember<EventPath> m_eventPath;
 };
 
 #define DEFINE_EVENT_TYPE_CASTS(typeName) \
     DEFINE_TYPE_CASTS(typeName, Event, event, event->is##typeName(), event.is##typeName())
 
 } // namespace WebCore
 
 #endif // Event_h