Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/dom/Node.h

Index: Source/core/dom/Node.h
diff --git a/Source/core/dom/Node.h b/Source/core/dom/Node.h
index 04c2a801fdf4c899b3ce949eff900076c7fa8915..ac00e5cd476808cef97c0e7d1bf1e6a643f2f0de 100644
--- a/Source/core/dom/Node.h
+++ b/Source/core/dom/Node.h
@@ -671,7 +671,7 @@ public:
 
     bool isFinishedParsingChildren() const { return getFlag(IsFinishedParsingChildrenFlag); }
 
-    virtual void trace(Visitor*) { }
+    virtual void trace(Visitor*);
 
 private:
     enum NodeFlags {
@@ -753,8 +753,10 @@ protected:
     {
         ASSERT(m_treeScope || type == CreateDocument || type == CreateShadowRoot);
         ScriptWrappable::init(this);
+#if !ENABLE(OILPAN)
         if (m_treeScope)
             m_treeScope->guardRef();
+#endif
 
 #if !defined(NDEBUG) || (defined(DUMP_NODE_STATISTICS) && DUMP_NODE_STATISTICS)
         trackForDebugging();
@@ -825,7 +827,7 @@ private:
 
     mutable uint32_t m_nodeFlags;
     ContainerNode* m_parentOrShadowHostNode;
-    TreeScope* m_treeScope;
+    RawPtrWillBeMember<TreeScope> m_treeScope;
     Node* m_previous;
     Node* m_next;
     // When a node has rare data we move the renderer into the rare data.