Bug 920425 part.6 Use mozilla::WidgetEvent::AsScrollAreaEvent() r=smaug

content/events/src/nsDOMEvent.cpp

@@ -632,8 +632,7 @@ nsDOMEvent::DuplicatePrivateData()
     }
     case NS_SCROLLAREA_EVENT:
     {
-      InternalScrollAreaEvent* oldScrollAreaEvent =
-        static_cast<InternalScrollAreaEvent*>(mEvent);
+      InternalScrollAreaEvent* oldScrollAreaEvent = mEvent->AsScrollAreaEvent();
       InternalScrollAreaEvent* scrollAreaEvent = 
         new InternalScrollAreaEvent(false, msg, nullptr);
       scrollAreaEvent->AssignScrollAreaEventData(*oldScrollAreaEvent, true);

content/events/src/nsEventDispatcher.cpp

@@ -700,7 +700,7 @@ nsEventDispatcher::CreateEvent(mozilla::dom::EventTarget* aOwner,
                               static_cast<WidgetGUIEvent*>(aEvent));
     case NS_SCROLLAREA_EVENT:
       return NS_NewDOMScrollAreaEvent(aDOMEvent, aOwner, aPresContext,
-               static_cast<InternalScrollAreaEvent*>(aEvent));
+                                      aEvent->AsScrollAreaEvent());
     case NS_KEY_EVENT:
       return NS_NewDOMKeyboardEvent(aDOMEvent, aOwner, aPresContext,
                                     static_cast<WidgetKeyboardEvent*>(aEvent));