Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/svg/animation/SVGSMILElement.h

Index: Source/core/svg/animation/SVGSMILElement.h
diff --git a/Source/core/svg/animation/SVGSMILElement.h b/Source/core/svg/animation/SVGSMILElement.h
index 3290a00b1385552c2e5d2b205bd869395984678d..9b7452b58459f1b1e96deecd516bf857758035e1 100644
--- a/Source/core/svg/animation/SVGSMILElement.h
+++ b/Source/core/svg/animation/SVGSMILElement.h
@@ -117,6 +117,8 @@ public:
 
     virtual bool isSVGDiscardElement() const { return false; }
 
+    void trace(Visitor*) OVERRIDE;
+
 protected:
     void addBeginTime(SMILTime eventTime, SMILTime endTime, SMILTimeWithOrigin::Origin = SMILTimeWithOrigin::ParserOrigin);
     void addEndTime(SMILTime eventTime, SMILTime endTime, SMILTimeWithOrigin::Origin = SMILTimeWithOrigin::ParserOrigin);
@@ -205,7 +207,7 @@ private:
     float calculateAnimationPercentAndRepeat(SMILTime elapsed, unsigned& repeat) const;
     SMILTime calculateNextProgressTime(SMILTime elapsed) const;
 
-    SVGElement* m_targetElement;
+    RawPtrWillBeMember<SVGElement> m_targetElement;
 
     Vector<Condition> m_conditions;
     bool m_syncBaseConditionsConnected;