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

Source/WebCore/editing/mac/FrameSelectionMac.mm

 /*
  * Copyright (C) 2007 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 @@
         bounds = CGRectZero;    
     
     return bounds;
 }
     
     
 void FrameSelection::notifyAccessibilityForSelectionChange()
 {
     Document* document = m_frame->document();
 
-    if (m_selection.start().isNotNull() && m_selection.end().isNotNull()) {
-        if (AXObjectCache* cache = document->existingAXObjectCache())
-            cache->postNotification(m_selection.start().deprecatedNode()->renderer(), AXObjectCache::AXSelectedTextChanged, false);
-    }
+    if (AXObjectCache::accessibilityEnabled() && m_selection.start().isNotNull() && m_selection.end().isNotNull())
+        document->axObjectCache()->postNotification(m_selection.start().deprecatedNode()->renderer(), AXObjectCache::AXSelectedTextChanged, false);
 
     // if zoom feature is enabled, insertion point changes should update the zoom
     if (!UAZoomEnabled() || !m_selection.isCaret())
         return;
 
     RenderView* renderView = document->renderView();
     if (!renderView)
         return;
     FrameView* frameView = m_frame->view();
     if (!frameView)
         return;
 
     IntRect selectionRect = absoluteCaretBounds();
     IntRect viewRect = pixelSnappedIntRect(renderView->viewRect());
 
     selectionRect = frameView->contentsToScreen(selectionRect);
     viewRect = frameView->contentsToScreen(viewRect);
     CGRect cgCaretRect = CGRectMake(selectionRect.x(), selectionRect.y(), selectionRect.width(), selectionRect.height());
     CGRect cgViewRect = CGRectMake(viewRect.x(), viewRect.y(), viewRect.width(), viewRect.height());
     cgCaretRect = accessibilityConvertScreenRect(cgCaretRect);
     cgViewRect = accessibilityConvertScreenRect(cgViewRect);
 
     UAZoomChangeFocus(&cgViewRect, &cgCaretRect, kUAZoomFocusTypeInsertionPoint);
 }
 
 } // namespace WebCore