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 f77f3fa23a0dbe8bb7c9fe7dc78724d8c04527a8..74b51a0d92a5ff5e6a1f69600b525cff758cb4e7 100644
--- a/Source/core/dom/Node.h
+++ b/Source/core/dom/Node.h
@@ -673,7 +673,7 @@ public:
 
     bool isFinishedParsingChildren() const { return getFlag(IsFinishedParsingChildrenFlag); }
 
-    virtual void trace(Visitor*) { }
+    virtual void trace(Visitor*);
 
 private:
     enum NodeFlags {
@@ -755,8 +755,10 @@ 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();
@@ -828,7 +830,7 @@ 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.