[oilpan] The Node hierarchy should have correct accept method chains

Source/core/dom/ShadowRoot.h

Index: Source/core/dom/ShadowRoot.h
diff --git a/Source/core/dom/ShadowRoot.h b/Source/core/dom/ShadowRoot.h
index b574fca3c1207c2f9b07dbc5f138540120cf0d78..7eca911b1610340ee38b5903c6e0eec32f4796a6 100644
--- a/Source/core/dom/ShadowRoot.h
+++ b/Source/core/dom/ShadowRoot.h
@@ -97,7 +97,7 @@ public:
     virtual void reportMemoryUsage(MemoryObjectInfo*) const OVERRIDE;
 
     virtual void visitWith(Visitor*) const;
-    virtual void acceptHeapVisitor(Visitor*) const;
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
 
 private:
     ShadowRoot(Handle<Document>, ShadowRootType);
@@ -112,6 +112,7 @@ private:
     // FIXME: This shouldn't happen. https://bugs.webkit.org/show_bug.cgi?id=88834
     bool isOrphan() const { return !host(); }
 
+    // FIXME(oilpan): Change these to Members. We will need to modify DoublyLinkListNode.
     ShadowRoot* m_prev;
     ShadowRoot* m_next;
     OwnPtr<ScopeContentDistribution> m_scopeDistribution;