Have getChildNodes() take a ContainerNode in argument

Source/core/editing/MergeIdenticalElementsCommand.cpp

 /*
  * Copyright (C) 2005, 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
@@ skipping 31 matching lines @@
     ASSERT(m_element1->nextSibling() == m_element2);
 }
 
 void MergeIdenticalElementsCommand::doApply()
 {
     if (m_element1->nextSibling() != m_element2 || !m_element1->hasEditableStyle() || !m_element2->hasEditableStyle())
         return;
 
     m_atChild = m_element2->firstChild();
 
-    WillBeHeapVector<RefPtrWillBeMember<Node> > children;
-    for (Node* child = m_element1->firstChild(); child; child = child->nextSibling())
-        children.append(child);
+    NodeVector children;
+    getChildNodes(*m_element1, children);
 
     size_t size = children.size();
     for (size_t i = 0; i < size; ++i)
         m_element2->insertBefore(children[i].release(), m_atChild.get(), IGNORE_EXCEPTION);
 
     m_element1->remove(IGNORE_EXCEPTION);
 }
 
 void MergeIdenticalElementsCommand::doUnapply()
 {
@@ skipping 23 matching lines @@
 
 void MergeIdenticalElementsCommand::trace(Visitor* visitor)
 {
     visitor->trace(m_element1);
     visitor->trace(m_element2);
     visitor->trace(m_atChild);
     SimpleEditCommand::trace(visitor);
 }
 
 } // namespace blink