IDL: Use Nullable for union type return value

Source/core/html/HTMLAllCollection.cpp

 /*
  * Copyright (C) 2009, 2011, 2012 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 48 matching lines @@
     }
 
     if (WillBeHeapVector<RawPtrWillBeMember<Element> >* elements = cache.getElementsByName(name)) {
         if (index < elements->size())
             return elements->at(index);
     }
 
     return 0;
 }
 
-void HTMLAllCollection::namedGetter(const AtomicString& name, bool& returnValue0Enabled, RefPtrWillBeRawPtr<NodeList>& returnValue0, bool& returnValue1Enabled, RefPtrWillBeRawPtr<Element>& returnValue1)
+void HTMLAllCollection::namedGetter(const AtomicString& name, RefPtrWillBeRawPtr<NodeList>& returnValue0, RefPtrWillBeRawPtr<Element>& returnValue1)
 {
     WillBeHeapVector<RefPtrWillBeMember<Element> > namedItems;
     this->namedItems(name, namedItems);
 
     if (!namedItems.size())
         return;
 
     if (namedItems.size() == 1) {
-        returnValue1Enabled = true;
         returnValue1 = namedItems.at(0);
         return;
     }
 
     // FIXME: HTML5 specification says this should be a HTMLCollection.
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#htmlallcollection
-    returnValue0Enabled = true;
     returnValue0 = StaticElementList::adopt(namedItems);
 }
 
 } // namespace blink