We should unify various forms of tree traversal in DOM

Source/core/dom/Node.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, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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
@@ skipping 153 matching lines @@
 
     virtual ~Node();
 
     // DOM methods & attributes for Node
 
     bool hasTagName(const QualifiedName&) const;
     virtual String nodeName() const = 0;
     virtual String nodeValue() const;
     virtual void setNodeValue(const String&);
     virtual NodeType nodeType() const = 0;
+    ContainerNode* parent() const { return parentNode(); }

[Inactive, 2014/01/07 14:37:03]

Longer term, we probably want to get rid of parentNode() and use
ImplementedAs=parent in Node.idl. parentNode() is used quite a lot of native
side also so this would be a big but mechanical change.

Maybe add a FIXME if others agree?

     ContainerNode* parentNode() const;
     Element* parentElement() const;
     Node* previousSibling() const { return m_previous; }
     Node* nextSibling() const { return m_next; }
     PassRefPtr<NodeList> childNodes();
     Node* firstChild() const;
     Node* lastChild() const;
 
     // ChildNode interface API
     Element* previousElementSibling() const;
@@ skipping 738 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const WebCore::Node*);
 void showNodePath(const WebCore::Node*);
 #endif
 
 #endif