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

Source/core/html/HTMLElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Motorola Mobility. 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
@@ skipping 186 matching lines @@
     if (!attrName.namespaceURI().isNull())
         return AtomicString();
     
     typedef HashMap<AtomicString, AtomicString> StringToStringMap;
     DEFINE_STATIC_LOCAL(StringToStringMap, attributeNameToEventNameMap, ());
     if (!attributeNameToEventNameMap.size()) {
         attributeNameToEventNameMap.set(onclickAttr.localName(), eventNames().clickEvent);
         attributeNameToEventNameMap.set(oncontextmenuAttr.localName(), eventNames().contextmenuEvent);
         attributeNameToEventNameMap.set(ondblclickAttr.localName(), eventNames().dblclickEvent);
         attributeNameToEventNameMap.set(onmousedownAttr.localName(), eventNames().mousedownEvent);
+        attributeNameToEventNameMap.set(onmouseenterAttr.localName(), eventNames().mouseenterEvent);
+        attributeNameToEventNameMap.set(onmouseleaveAttr.localName(), eventNames().mouseleaveEvent);
         attributeNameToEventNameMap.set(onmousemoveAttr.localName(), eventNames().mousemoveEvent);
         attributeNameToEventNameMap.set(onmouseoutAttr.localName(), eventNames().mouseoutEvent);
         attributeNameToEventNameMap.set(onmouseoverAttr.localName(), eventNames().mouseoverEvent);
         attributeNameToEventNameMap.set(onmouseupAttr.localName(), eventNames().mouseupEvent);
         attributeNameToEventNameMap.set(onmousewheelAttr.localName(), eventNames().mousewheelEvent);
         attributeNameToEventNameMap.set(onfocusAttr.localName(), eventNames().focusEvent);
         attributeNameToEventNameMap.set(onfocusinAttr.localName(), eventNames().focusinEvent);
         attributeNameToEventNameMap.set(onfocusoutAttr.localName(), eventNames().focusoutEvent);
         attributeNameToEventNameMap.set(onblurAttr.localName(), eventNames().blurEvent);
         attributeNameToEventNameMap.set(onkeydownAttr.localName(), eventNames().keydownEvent);
@@ skipping 873 matching lines @@
 #ifndef NDEBUG
 
 // For use in the debugger
 void dumpInnerHTML(WebCore::HTMLElement*);
 
 void dumpInnerHTML(WebCore::HTMLElement* element)
 {
     printf("%s\n", element->innerHTML().ascii().data());
 }
 #endif