Move Node/ContainerNode's traverseToChildAt() to NodeTraversal

Source/core/dom/ContainerNode.cpp

 /*
  * 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, 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 1087 matching lines @@
 
 unsigned ContainerNode::countChildren() const
 {
     unsigned count = 0;
     Node *n;
     for (n = firstChild(); n; n = n->nextSibling())
         count++;
     return count;
 }
 
-Node* ContainerNode::traverseToChildAt(unsigned index) const
-{
-    unsigned i;
-    Node *n = firstChild();
-    for (i = 0; n != 0 && i < index; i++)
-        n = n->nextSibling();
-    return n;
-}
-
 PassRefPtrWillBeRawPtr<Element> ContainerNode::querySelector(const AtomicString& selectors, ExceptionState& exceptionState)
 {
     if (selectors.isEmpty()) {
         exceptionState.throwDOMException(SyntaxError, "The provided selector is empty.");
         return nullptr;
     }
 
     SelectorQuery* selectorQuery = document().selectorQueryCache().add(selectors, document(), exceptionState);
     if (!selectorQuery)
         return nullptr;
@@ skipping 293 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace blink