Move Node/ContainerNode's traverseToChildAt() to NodeTraversal

Source/core/dom/PositionIterator.h

 /*
  * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef PositionIterator_h
 #define PositionIterator_h
 
 #include "core/dom/Node.h"
+#include "core/dom/NodeTraversal.h"
 #include "core/dom/Position.h"
 
 namespace blink {
 
 // A Position iterator with constant-time
 // increment, decrement, and several predicates on the Position it is at.
 // Conversion to/from Position is O(n) in the offset.
 class PositionIterator {
     STACK_ALLOCATED();
 public:
     PositionIterator()
         : m_anchorNode(nullptr)
         , m_nodeAfterPositionInAnchor(nullptr)
         , m_offsetInAnchor(0)
     {
     }
 
     PositionIterator(const Position& pos)
         : m_anchorNode(pos.anchorNode())
-        , m_nodeAfterPositionInAnchor(m_anchorNode->traverseToChildAt(pos.deprecatedEditingOffset()))
+        , m_nodeAfterPositionInAnchor(NodeTraversal::childAt(*m_anchorNode, pos.deprecatedEditingOffset()))
         , m_offsetInAnchor(m_nodeAfterPositionInAnchor ? 0 : pos.deprecatedEditingOffset())
     {
     }
     operator Position() const;
 
     void increment();
     void decrement();
 
     Node* node() const { return m_anchorNode; }
     int offsetInLeafNode() const { return m_offsetInAnchor; }
 
     bool atStart() const;
     bool atEnd() const;
     bool atStartOfNode() const;
     bool atEndOfNode() const;
     bool isCandidate() const;
 
 private:
     RawPtrWillBeMember<Node> m_anchorNode;
     RawPtrWillBeMember<Node> m_nodeAfterPositionInAnchor; // If this is non-null, m_nodeAfterPositionInAnchor->parentNode() == m_anchorNode;
     int m_offsetInAnchor;
 };
 
 } // namespace blink
 
 #endif // PositionIterator_h