Have Node::highestAncestor() return a reference

Source/core/dom/ContainerNode.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 225 matching lines @@
     return toContainerNode(this)->firstChild();
 }
 
 inline Node* Node::lastChild() const
 {
     if (!isContainerNode())
         return 0;
     return toContainerNode(this)->lastChild();
 }
 
-inline Node* Node::highestAncestor() const
+inline Node& Node::highestAncestor() const
 {
     Node* node = const_cast<Node*>(this);
     Node* highest = node;
     for (; node; node = node->parentNode())
         highest = node;
-    return highest;
+    return *highest;
 }
 
 inline Node* Node::parentElementOrShadowRoot() const
 {
     ContainerNode* parent = parentNode();
     return parent && (parent->isElementNode() || parent->isShadowRoot()) ? parent : 0;
 }
 
 // This constant controls how much buffer is initially allocated
 // for a Node Vector that is used to store child Nodes of a given Node.
@@ skipping 69 matching lines @@
 
     RefPtr<Node> m_currentNode;
     unsigned m_currentIndex;
     OwnPtr<Vector<RefPtr<Node> > > m_childNodes; // Lazily instantiated.
     ChildNodesLazySnapshot* m_nextSnapshot;
 };
 
 } // namespace WebCore
 
 #endif // ContainerNode_h