Revert 146726 "AXObjectCache gets recreated during document tear..."

Source/WebCore/editing/AppendNodeCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 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 34 matching lines @@
     ASSERT(m_parent->rendererIsEditable() || !m_parent->attached());
 }
 
 static void sendAXTextChangedIgnoringLineBreaks(Node* node, AXObjectCache::AXTextChange textChange)
 {
     String nodeValue = node->nodeValue();
     // Don't consider linebreaks in this command
     if (nodeValue == "\n")
       return;
 
-    if (AXObjectCache* cache = node->document()->existingAXObjectCache())
-        cache->nodeTextChangeNotification(node, textChange, 0, nodeValue);
+    node->document()->axObjectCache()->nodeTextChangeNotification(node, textChange, 0, nodeValue);
 }
 
 void AppendNodeCommand::doApply()
 {
     if (!m_parent->rendererIsEditable() && m_parent->attached())
         return;
 
     m_parent->appendChild(m_node.get(), IGNORE_EXCEPTION, AttachLazily);
 
     if (AXObjectCache::accessibilityEnabled())
@@ skipping 14 matching lines @@
 
 #ifndef NDEBUG
 void AppendNodeCommand::getNodesInCommand(HashSet<Node*>& nodes)
 {
     addNodeAndDescendants(m_parent.get(), nodes);
     addNodeAndDescendants(m_node.get(), nodes);
 }
 #endif
 
 } // namespace WebCore