Implement 'mouseenter' and 'mouseleave' from DOM Level 3 Events.

Source/core/page/DOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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 274 matching lines @@
         DEFINE_ATTRIBUTE_EVENT_LISTENER(invalid);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(keydown);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(keypress);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(keyup);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(load);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(loadeddata);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(loadedmetadata);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(loadstart);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(message);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mousedown);
+        DEFINE_ATTRIBUTE_EVENT_LISTENER(mouseenter);
+        DEFINE_ATTRIBUTE_EVENT_LISTENER(mouseleave);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mousemove);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mouseout);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mouseover);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mouseup);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(mousewheel);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(offline);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(online);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(pagehide);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(pageshow);
         DEFINE_ATTRIBUTE_EVENT_LISTENER(pause);
@@ skipping 128 matching lines @@
     }
 
     inline String DOMWindow::defaultStatus() const
     {
         return m_defaultStatus;
     } 
 
 } // namespace WebCore
 
 #endif // DOMWindow_h