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

Source/WebCore/html/InputType.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2009, 2010, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 Samsung Electronics. All rights reserved.
  *
@@ skipping 995 matching lines @@
 
     if (newValue - stepRange.maximum() > acceptableErrorValue) {
         ec = INVALID_STATE_ERR;
         return;
     }
     if (newValue > stepRange.maximum())
         newValue = stepRange.maximum();
 
     setValueAsDecimal(newValue, eventBehavior, ec);
 
-    if (AXObjectCache* cache = element()->document()->existingAXObjectCache())
-        cache->postNotification(element(), AXObjectCache::AXValueChanged, true);
+    if (AXObjectCache::accessibilityEnabled())
+         element()->document()->axObjectCache()->postNotification(element(), AXObjectCache::AXValueChanged, true);
 }
 
 bool InputType::getAllowedValueStep(Decimal* step) const
 {
     StepRange stepRange(createStepRange(RejectAny));
     *step = stepRange.step();
     return stepRange.hasStep();
 }
 
 StepRange InputType::createStepRange(AnyStepHandling) const
@@ skipping 114 matching lines @@
 
 void InputType::observeFeatureIfVisible(FeatureObserver::Feature feature) const
 {
     if (RenderStyle* style = element()->renderStyle()) {
         if (style->visibility() != HIDDEN)
             FeatureObserver::observe(element()->document(), feature);
     }
 }
 
 } // namespace WebCore