Have NodeTraversal::previous*() take a reference

Source/core/html/HTMLCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2011, 2012 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 237 matching lines @@
     return nodeList->nodeMatchesInlined(element);
 }
 
 template <> inline bool isMatchingElement(const ClassNodeList* nodeList, Element* element)
 {
     return nodeList->nodeMatchesInlined(element);
 }
 
 static Node* previousNode(Node& base, Node& previous, bool onlyIncludeDirectChildren)
 {
-    return onlyIncludeDirectChildren ? previous.previousSibling() : NodeTraversal::previous(&previous, &base);
+    return onlyIncludeDirectChildren ? previous.previousSibling() : NodeTraversal::previous(previous, &base);
 }
 
 static inline Node* lastDescendent(Node& node)
 {
     Node* descendent = node.lastChild();
     for (Node* current = descendent; current; current = current->lastChild())
         descendent = current;
     return descendent;
 }
 
@@ skipping 413 matching lines @@
 
 void HTMLCollection::append(NodeCacheMap& map, const AtomicString& key, Element* element)
 {
     OwnPtr<Vector<Element*> >& vector = map.add(key.impl(), nullptr).iterator->value;
     if (!vector)
         vector = adoptPtr(new Vector<Element*>);
     vector->append(element);
 }
 
 } // namespace WebCore