Handle (numeric) indexed access of DOMStringMap.

Source/core/dom/DOMStringMap.h

 /*
  * Copyright (C) 2010 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 55 matching lines @@
         // delete document.body.dataset["-foo"] // false instead of DOM Exception 12
         // LayoutTests/fast/dom/HTMLSelectElement/select-selectedIndex-multiple.html
         return result;
     }
     void namedPropertyEnumerator(Vector<String>& names, ExceptionState&)
     {
         getNames(names);
     }
     bool namedPropertyQuery(const AtomicString&, ExceptionState&);
 
+    String anonymousIndexedGetter(uint32_t index)
+    {
+        return item(String::number(index));
+    }
+    bool anonymousIndexedSetter(uint32_t index, const String& value, ExceptionState& es)
+    {
+        return anonymousNamedSetter(String::number(index), value, es);
+    }
+    bool anonymousIndexedDeleter(uint32_t index, ExceptionState& es)
+    {
+        return anonymousNamedDeleter(AtomicString(String::number(index)), es);
+    }
+
     virtual Element* element() = 0;
 
 protected:
     DOMStringMap()
     {
         ScriptWrappable::init(this);
     }
 };
 
 } // namespace WebCore
 
 #endif // DOMStringMap_h