Support union return type for anonymous named/indexed getter

Source/wtf/UnionType.h

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef StringStatics_h
-#define StringStatics_h
+#ifndef UnionType_h
+#define UnionType_h
 
 namespace WTF {
 
-class StringStatics {
+// UnionTypeN holds multiple types of objects.
+//
+// WebIDL(UnionType):
+// http://www.w3.org/TR/WebIDL/#prod-UnionType
+//
+// Example IDL:
+// http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#htmlformcontrolscollection
+template<typename Type1, typename Type2>
+class UnionType2 {
 public:
-    static void init();
-
+    UnionType2()
+    {
+    }
+    explicit UnionType2(PassRefPtr<Type1> value)
+    {
+        m_value1 = value;
+    }
+    explicit UnionType2(PassRefPtr<Type2> value)
+    {
+        m_value2 = value;
+    }
+    bool isNull() const
+    {
+        return !m_value1 && !m_value2;
+    }
+    PassRefPtr<Type1> member1() const
+    {
+        return m_value1;
+    }
+    PassRefPtr<Type2> member2() const
+    {
+        return m_value2;
+    }
 private:
-    StringStatics();
+    RefPtr<Type1> m_value1;
+    RefPtr<Type2> m_value2;
 };
 
-}
 
-#endif
+} // namespace WTF
+
+#endif // UnionType_h