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

Source/WebCore/editing/chromium/FrameSelectionChromium.cpp

 /*
  * Copyright (C) 2010 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 22 matching lines @@
 
 #include "AXObjectCache.h"
 #include "Document.h"
 #include "Frame.h"
 
 namespace WebCore {
 
 void FrameSelection::notifyAccessibilityForSelectionChange()
 {
     // FIXME: Support editable text in chromium.
-    if (m_selection.start().isNotNull() && m_selection.end().isNotNull()) {
-        if (AXObjectCache* cache = m_frame->document()->existingAXObjectCache())
-            cache->postNotification(m_selection.start().deprecatedNode(), AXObjectCache::AXSelectedTextChanged, false);
+    if (AXObjectCache::accessibilityEnabled() && m_selection.start().isNotNull() && m_selection.end().isNotNull()) {
+        Document* document = m_frame->document();
+        document->axObjectCache()->postNotification(m_selection.start().deprecatedNode(), AXObjectCache::AXSelectedTextChanged, false);
     }
 }
 
 } // namespace WebCore