Move Node/ContainerNode's traverseToChildAt() to NodeTraversal

Source/core/editing/InsertParagraphSeparatorCommand.cpp

 /*
  * Copyright (C) 2005, 2006 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 265 matching lines @@
                 insertNodeBefore(listChildToInsert.get(), listChild);
             } else {
                 refNode = startBlock.get();
             }
         } else if (isFirstInBlock && nestNewBlock) {
             // startBlock should always have children, otherwise isLastInBlock would be true and it's handled above.
             ASSERT(startBlock->hasChildren());
             refNode = startBlock->firstChild();
         }
         else if (insertionPosition.deprecatedNode() == startBlock && nestNewBlock) {
-            refNode = startBlock->traverseToChildAt(insertionPosition.deprecatedEditingOffset());
+            refNode = NodeTraversal::childAt(*startBlock, insertionPosition.deprecatedEditingOffset());
             ASSERT(refNode); // must be true or we'd be in the end of block case
         } else
             refNode = insertionPosition.deprecatedNode();
 
         // find ending selection position easily before inserting the paragraph
         insertionPosition = insertionPosition.downstream();
 
         if (refNode)
             insertNodeBefore(blockToInsert, refNode);
 
@@ skipping 132 matching lines @@
 }
 
 void InsertParagraphSeparatorCommand::trace(Visitor *visitor)
 {
     visitor->trace(m_style);
     CompositeEditCommand::trace(visitor);
 }
 
 
 } // namespace blink