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

Source/core/dom/EventTarget.h

Index: Source/core/dom/EventTarget.h
diff --git a/Source/core/dom/EventTarget.h b/Source/core/dom/EventTarget.h
index db533917b47fd9fecb02934367360ca8c5220bd2..5b736ed19e76a8a07f0b5bde0e40b882c4e850f0 100644
--- a/Source/core/dom/EventTarget.h
+++ b/Source/core/dom/EventTarget.h
@@ -121,6 +121,7 @@ namespace WebCore {
 
         bool hasEventListeners();
         bool hasEventListeners(const AtomicString& eventType);
+        bool hasCapturingEventListeners(const AtomicString& eventType);
         const EventListenerVector& getEventListeners(const AtomicString& eventType);
 
         bool fireEventListeners(Event*);
@@ -197,6 +198,14 @@ namespace WebCore {
         return d->eventListenerMap.contains(eventType);
     }
 
+    inline bool EventTarget::hasCapturingEventListeners(const AtomicString& eventType)
+    {
+        EventTargetData* d = eventTargetData();
+        if (!d)
+            return false;
+        return d->eventListenerMap.containsCapturing(eventType);
+    }
+
 } // namespace WebCore
 
 #endif // EventTarget_h