Oilpan: Make the Node hierarchy RefCountedGarbageCollected instead of TreeShared.

Source/core/testing/LayerRect.h

Index: Source/core/testing/LayerRect.h
diff --git a/Source/core/testing/LayerRect.h b/Source/core/testing/LayerRect.h
index 7074c225956531ed2a89599fb42091ea22bb5b34..f47b7e00a02d84f4a446df5d88d3c09f7a2aa27c 100644
--- a/Source/core/testing/LayerRect.h
+++ b/Source/core/testing/LayerRect.h
@@ -58,6 +58,7 @@ public:
 
     void trace(Visitor* visitor)
     {
+        visitor->trace(m_layerAssociatedNode);
         visitor->trace(m_rect);
     }
 
@@ -71,7 +72,7 @@ private:
     {
     }
 
-    RefPtr<Node> m_layerAssociatedNode;
+    RefPtrWillBeMember<Node> m_layerAssociatedNode;
     String m_layerType;
     int m_associatedNodeOffsetX;
     int m_associatedNodeOffsetY;