Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 2333 matching lines @@
         Widget* widget = toRenderWidget(renderer)->widget();
         return widget && passGestureEventToWidget(gestureEvent, widget);
     }
     return false;
 }
 
 bool EventHandler::handleGestureScrollEnd(const PlatformGestureEvent& gestureEvent) {
     RefPtr<Node> node = m_scrollGestureHandlingNode;
     clearGestureScrollNodes();
 
-    if (node) {
-        ASSERT(node->refCount() > 0);
+    if (node)
         passGestureEventToWidgetIfPossible(gestureEvent, node->renderer());
-    }
 
     return false;
 }
 
 bool EventHandler::handleGestureScrollBegin(const PlatformGestureEvent& gestureEvent)
 {
     Document* document = m_frame->document();
     if (!document->renderView())
         return false;
 
@@ skipping 1364 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore