Oilpan: Prepare to move RenderObject and RenderObjectChildList to Oilpan heap.

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index ecfc9ad215db1c3d645c5bb1d9707fbb19dae604..06141c8ccdfd1dda46f8973c1dcf0f4b8a4c5866 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -145,7 +145,7 @@ const int showTreeCharacterOffset = 39;
 #endif
 
 // Base class for all rendering tree objects.
-class RenderObject : public ImageResourceClient {
+class RenderObject : public NoBaseWillBeGarbageCollectedFinalized<RenderObject>, public ImageResourceClient {
     friend class RenderBlock;
     friend class RenderBlockFlow;
     friend class RenderLayerReflectionInfo; // For setParent
@@ -157,6 +157,7 @@ public:
     // marked as anonymous in the constructor.
     explicit RenderObject(Node*);
     virtual ~RenderObject();
+    virtual void trace(Visitor*);
 
     virtual const char* renderName() const = 0;
 
@@ -343,9 +344,11 @@ public:
     static RenderObject* createObject(Element*, RenderStyle*);
     static unsigned instanceCount() { return s_instanceCount; }
 
+#if !ENABLE(OILPAN)
     // RenderObjects are allocated out of the rendering partition.
     void* operator new(size_t);
     void operator delete(void*);
+#endif
 
 public:
     bool isPseudoElement() const { return node() && node()->isPseudoElement(); }
@@ -627,7 +630,7 @@ public:
 
     Node* node() const
     {
-        return isAnonymous() ? 0 : m_node;
+        return isAnonymous() ? 0 : m_node.get();
     }
 
     Node* nonPseudoNode() const
@@ -636,7 +639,7 @@ public:
     }
 
     // FIXME: Why does RenderWidget need this?
-    void clearNode() { m_node = 0; }
+    void clearNode() { m_node = nullptr; }
 
     // Returns the styled node that caused the generation of this renderer.
     // This is the same as node() except for renderers of :before and :after
@@ -1185,15 +1188,20 @@ private:
 
     RefPtr<RenderStyle> m_style;
 
-    Node* m_node;
+    RawPtrWillBeMember<Node> m_node;
 
-    RenderObject* m_parent;
-    RenderObject* m_previous;
-    RenderObject* m_next;
+    RawPtrWillBeMember<RenderObject> m_parent;
+    RawPtrWillBeMember<RenderObject> m_previous;
+    RawPtrWillBeMember<RenderObject> m_next;
 
 #if ENABLE(ASSERT)
     unsigned m_hasAXObject             : 1;
     unsigned m_setNeedsLayoutForbidden : 1;
+#if ENABLE(OILPAN)
+protected:
+    unsigned m_didCallDestroy          : 1;
+private:
+#endif
 #endif
 
 #define ADD_BOOLEAN_BITFIELD(name, Name) \