We should unify various forms of tree traversal in DOM

Source/core/html/HTMLImport.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 46 matching lines @@
     if (lastChild() && lastChild()->isBlockingFollowersFromCreatingDocument())
         child->blockFromCreatingDocument();
     TreeNode<HTMLImport>::appendChild(child);
     if (child->isCreatedByParser())
         blockPredecessorsOf(child);
 }
 
 inline bool HTMLImport::isBlockedFromCreatingDocumentByPredecessors() const
 {
     ASSERT(isBlockedFromCreatingDocument());
-    HTMLImport* elder = previous();
+    HTMLImport* elder = previousSibling();
     return (elder && !elder->isDone());
 }
 
 bool HTMLImport::isBlockedFromRunningScriptByPredecessors() const
 {
     HTMLImport* parent = this->parent();
     if (!parent)
         return false;
 
-    for (HTMLImport* sibling = parent->firstChild(); sibling; sibling = sibling->next()) {
+    for (HTMLImport* sibling = parent->firstChild(); sibling; sibling = sibling->nextSibling()) {
         if (sibling == this)
             break;
         if (sibling->isBlockingFollowersFromRunningScript())
             return true;
     }
 
     return false;
 }
 
 void HTMLImport::blockFromRunningScript()
@@ skipping 52 matching lines @@
 }
 
 bool HTMLImport::unblock(HTMLImport* import)
 {
     ASSERT(!import->isBlockedFromRunningScriptByPredecessors());
 
     if (import->isBlockedFromCreatingDocument() && import->isBlockedFromCreatingDocumentByPredecessors())
         return false;
     import->unblockFromCreatingDocument();
 
-    for (HTMLImport* child = import->firstChild(); child; child = child->next()) {
+    for (HTMLImport* child = import->firstChild(); child; child = child->nextSibling()) {
         if (!unblock(child))
             return false;
     }
 
     import->unblockFromRunningScript();
 
     return !import->isBlockingFollowersFromRunningScript();
 }
 
 void HTMLImport::block(HTMLImport* import)
 {
-    for (HTMLImport* child = import; child; child = traverseNext(child, import))
+    for (HTMLImport* child = import; child; child = traverseNext(*child, import))
         child->blockFromRunningScript();
 }
 
 void HTMLImport::blockPredecessorsOf(HTMLImport* child)
 {
     ASSERT(child->parent() == this);
 
-    for (HTMLImport* sibling = lastChild(); sibling; sibling = sibling->previous()) {
+    for (HTMLImport* sibling = lastChild(); sibling; sibling = sibling->previousSibling()) {
         if (sibling == child)
             break;
         HTMLImport::block(sibling);
     }
 
     this->blockFromRunningScript();
 
     if (HTMLImport* parent = this->parent()) {
         if (isCreatedByParser())
             parent->blockPredecessorsOf(this);
     }
 }
 
 bool HTMLImport::isMaster(Document* document)
 {
     if (!document->import())
         return true;
     return (document->import()->master() == document);
 }
 
 } // namespace WebCore