Slightly upgrade caching of descendant of barren parent.

Source/modules/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 413 matching lines @@
 }
 
 bool AXObject::isDescendantOfBarrenParent() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedIsDescendantOfBarrenParent;
 }
 
 bool AXObject::computeIsDescendantOfBarrenParent() const
 {
-    for (AXObject* object = parentObject(); object; object = object->parentObject()) {
-        if (!object->canHaveChildren())
+    if (AXObject* parent = parentObject()) {
+        if (!parent->canHaveChildren())
             return true;
+
+        return parent->isDescendantOfBarrenParent();
     }
 
     return false;
 }
 
 const AXObject* AXObject::ariaHiddenRoot() const
 {
     for (const AXObject* object = this; object; object = object->parentObject()) {
         if (equalIgnoringCase(object->getAttribute(aria_hiddenAttr), "true"))
             return object;
@@ skipping 696 matching lines @@
 }
 
 const AtomicString& AXObject::roleName(AccessibilityRole role)
 {
     static const Vector<AtomicString>* roleNameVector = createRoleNameVector();
 
     return roleNameVector->at(role);
 }
 
 } // namespace blink