Oilpan: Prepare to move EventDispatchMediator to Oilpan heap.

Source/core/events/WheelEvent.cpp

Index: Source/core/events/WheelEvent.cpp
diff --git a/Source/core/events/WheelEvent.cpp b/Source/core/events/WheelEvent.cpp
index a00b598ee7f78c0089704cb67018f9e245df7748..7a1e16e5f9bfe618665fda35d8f3f04dd451121f 100644
--- a/Source/core/events/WheelEvent.cpp
+++ b/Source/core/events/WheelEvent.cpp
@@ -135,9 +135,9 @@ inline static unsigned deltaMode(const PlatformWheelEvent& event)
     return event.granularity() == ScrollByPageWheelEvent ? WheelEvent::DOM_DELTA_PAGE : WheelEvent::DOM_DELTA_PIXEL;
 }
 
-PassRefPtr<WheelEventDispatchMediator> WheelEventDispatchMediator::create(const PlatformWheelEvent& event, PassRefPtrWillBeRawPtr<AbstractView> view)
+PassRefPtrWillBeRawPtr<WheelEventDispatchMediator> WheelEventDispatchMediator::create(const PlatformWheelEvent& event, PassRefPtrWillBeRawPtr<AbstractView> view)
 {
-    return adoptRef(new WheelEventDispatchMediator(event, view));
+    return adoptRefWillBeNoop(new WheelEventDispatchMediator(event, view));
 }
 
 WheelEventDispatchMediator::WheelEventDispatchMediator(const PlatformWheelEvent& event, PassRefPtrWillBeRawPtr<AbstractView> view)