Move highestAncestorOrSelf() from Node to NodeTraversal

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, 2013 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 277 matching lines @@
     return toContainerNode(this)->firstChild();
 }
 
 inline Node* Node::lastChild() const
 {
     if (!isContainerNode())
         return 0;
     return toContainerNode(this)->lastChild();
 }
 
-inline Node& Node::highestAncestorOrSelf() const
-{
-    Node* node = const_cast<Node*>(this);
-    Node* highest = node;
-    for (; node; node = node->parentNode())
-        highest = node;
-    return *highest;
-}
-
 inline ContainerNode* Node::parentElementOrShadowRoot() const
 {
     ContainerNode* parent = parentNode();
     return parent && (parent->isElementNode() || parent->isShadowRoot()) ? parent : 0;
 }
 
 inline ContainerNode* Node::parentElementOrDocumentFragment() const
 {
     ContainerNode* parent = parentNode();
     return parent && (parent->isElementNode() || parent->isDocumentFragment()) ? parent : 0;
 }
 
 inline bool Node::isTreeScope() const
 {
     return &treeScope().rootNode() == this;
 }
 
 inline void getChildNodes(Node& node, NodeVector& nodes)
 {
     ASSERT(!nodes.size());
     for (Node* child = node.firstChild(); child; child = child->nextSibling())
         nodes.append(child);
 }
 
 } // namespace blink
 
 #endif // ContainerNode_h