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

Source/core/events/EventPath.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 363 matching lines @@
 #ifndef NDEBUG
 void EventPath::checkReachability(TreeScope& treeScope, TouchList& touchList)
 {
     for (size_t i = 0; i < touchList.length(); ++i)
         ASSERT(touchList.item(i)->target()->toNode()->treeScope().isInclusiveOlderSiblingShadowRootOrAncestorTreeScopeOf(treeScope));
 }
 #endif
 
 void EventPath::trace(Visitor* visitor)
 {
+    visitor->trace(m_nodeEventContexts);
     visitor->trace(m_event);
 }
 
 } // namespace