Oilpan: Replace RefPtrs to Node and its subclasses in core/events/ with Oilpan transition types.

Source/core/events/EventDispatcher.h

Index: Source/core/events/EventDispatcher.h
diff --git a/Source/core/events/EventDispatcher.h b/Source/core/events/EventDispatcher.h
index fc84e83596f90a9243c12226f1326a44c09a86dc..f753adc82aef3da3466009619530c36fa6cfbd78 100644
--- a/Source/core/events/EventDispatcher.h
+++ b/Source/core/events/EventDispatcher.h
@@ -46,6 +46,7 @@ enum EventDispatchContinuation {
 };
 
 class EventDispatcher {
+    STACK_ALLOCATED();
 public:
     static bool dispatchEvent(Node*, PassRefPtr<EventDispatchMediator>);
     static void dispatchScopedEvent(Node*, PassRefPtr<EventDispatchMediator>);
@@ -66,8 +67,8 @@ private:
     void dispatchEventAtBubbling(WindowEventContext&);
     void dispatchEventPostProcess(void* preDispatchEventHandlerResult);
 
-    RefPtr<Node> m_node;
-    RefPtrWillBePersistent<Event> m_event;
+    RefPtrWillBeMember<Node> m_node;
+    RefPtrWillBeMember<Event> m_event;
     RefPtr<FrameView> m_view;
 #ifndef NDEBUG
     bool m_eventDispatched;