IDL: Generate union type containers

Source/core/html/HTMLAllCollection.h

 /*
  * Copyright (C) 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 12 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLAllCollection_h
 #define HTMLAllCollection_h
 
 #include "core/html/HTMLCollection.h"
 
 namespace blink {
 
+class NodeListOrElement;
+
 class HTMLAllCollection final : public HTMLCollection {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<HTMLAllCollection> create(ContainerNode&, CollectionType);
     virtual ~HTMLAllCollection();
 
     Element* namedItemWithIndex(const AtomicString& name, unsigned index) const;
-    void namedGetter(const AtomicString& name, RefPtrWillBeRawPtr<NodeList>&, RefPtrWillBeRawPtr<Element>&);
+    void namedGetter(const AtomicString& name, NodeListOrElement&);
 
 private:
     explicit HTMLAllCollection(ContainerNode&);
 };
 
 DEFINE_TYPE_CASTS(HTMLAllCollection, LiveNodeListBase, collection, collection->type() == DocAll, collection.type() == DocAll);
 
 } // namespace blink
 
 #endif // HTMLAllCollection_h