Made ARIA alerts have an implicit aria-atomic of true and strengthened tests concerning aria-atomic…

third_party/WebKit/Source/modules/accessibility/AXLayoutObject.cpp

 /*
 * Copyright (C) 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
@@ skipping 1385 matching lines @@
 
     // Default aria-relevant = "additions text".
     if (relevant.isEmpty())
         return defaultLiveRegionRelevant;
 
     return relevant;
 }
 
 bool AXLayoutObject::liveRegionAtomic() const
 {
-    // ARIA role status should have implicit aria-atomic value of true.
-    if (getAttribute(aria_atomicAttr).isEmpty() && roleValue() == StatusRole)
+    // ARIA roles "alert" and "status" should have an implicit aria-atomic value of true.
+    if (getAttribute(aria_atomicAttr).isEmpty()
+        && (roleValue() == AlertRole || roleValue() == StatusRole)) {
         return true;
+    }
     return elementAttributeValue(aria_atomicAttr);
 }
 
 bool AXLayoutObject::liveRegionBusy() const
 {
     return elementAttributeValue(aria_busyAttr);
 }
 
 //
 // Position and size.
@@ skipping 1160 matching lines @@
                     result.unite(labelRect);
                 }
             }
         }
     }
 
     return result;
 }
 
 } // namespace blink