Remove more oilpan.

sky/engine/core/dom/TreeScope.h

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 26 matching lines @@
 class DOMSelection;
 class Document;
 class Element;
 class HitTestResult;
 class ScopedStyleResolver;
 class Node;
 
 // A class which inherits both Node and TreeScope must call clearRareData() in its destructor
 // so that the Node destructor no longer does problematic NodeList cache manipulation in
 // the destructor.
-class TreeScope : public DummyBase<void> {
+class TreeScope {
 public:
     TreeScope* parentTreeScope() const { return m_parentTreeScope; }
 
     TreeScope* olderShadowRootOrParentTreeScope() const;
     bool isInclusiveOlderSiblingShadowRootOrAncestorTreeScopeOf(const TreeScope&) const;
 
     Element* adjustedFocusedElement() const;
     Element* getElementById(const AtomicString&) const;
     void addElementById(const AtomicString& elementId, Element*);
     void removeElementById(const AtomicString& elementId, Element*);
@@ skipping 114 matching lines @@
 };
 
 DEFINE_COMPARISON_OPERATORS_WITH_REFERENCES(TreeScope)
 
 HitTestResult hitTestInDocument(const Document*, int x, int y);
 TreeScope* commonTreeScope(Node*, Node*);
 
 } // namespace blink
 
 #endif // TreeScope_h