Move Node/ContainerNode's traverseToChildAt() to NodeTraversal

Source/core/editing/DeleteSelectionCommand.cpp

 /*
  * Copyright (C) 2005 Apple Computer, 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
@@ skipping 487 matching lines @@
         // The selection to delete spans more than one node.
         RefPtrWillBeRawPtr<Node> node(startNode);
 
         if (startOffset > 0) {
             if (startNode->isTextNode()) {
                 // in a text node that needs to be trimmed
                 Text* text = toText(node);
                 deleteTextFromNode(text, startOffset, text->length() - startOffset);
                 node = NodeTraversal::next(*node);
             } else {
-                node = startNode->traverseToChildAt(startOffset);
+                node = NodeTraversal::childAt(*startNode, startOffset);
             }
         } else if (startNode == m_upstreamEnd.deprecatedNode() && startNode->isTextNode()) {
             Text* text = toText(m_upstreamEnd.deprecatedNode());
             deleteTextFromNode(text, 0, m_upstreamEnd.deprecatedEditingOffset());
         }
 
         // handle deleting all nodes that are completely selected
         while (node && node != m_downstreamEnd.deprecatedNode()) {
             if (comparePositions(firstPositionInOrBeforeNode(node.get()), m_downstreamEnd) >= 0) {
                 // NodeTraversal::nextSkippingChildren just blew past the end position, so stop deleting
@@ skipping 370 matching lines @@
     visitor->trace(m_deleteIntoBlockquoteStyle);
     visitor->trace(m_startRoot);
     visitor->trace(m_endRoot);
     visitor->trace(m_startTableRow);
     visitor->trace(m_endTableRow);
     visitor->trace(m_temporaryPlaceholder);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink