Treat inert nodes as aria-hidden instead of aria-disabled.

Source/core/accessibility/AXObject.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 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
@@ skipping 954 matching lines @@
     // We don't contemplate RadioButtonRole, as it depends on the input
     // type.
 
     return ButtonRole;
 }
 
 bool AXObject::ariaIsHidden() const
 {
     if (equalIgnoringCase(getAttribute(aria_hiddenAttr), "true"))
         return true;
+    if (node() && node()->isInert())
+        return true;
 
     for (AXObject* object = parentObject(); object; object = object->parentObject()) {
         if (equalIgnoringCase(object->getAttribute(aria_hiddenAttr), "true"))
             return true;
     }
 
     return false;
 }
 
 } // namespace WebCore