Add number() static methods to AtomicString class

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 65 matching lines @@
     String anonymousIndexedGetter(uint32_t index)
     {
         return item(String::number(index));
     }
     bool anonymousIndexedSetter(uint32_t index, const String& value, ExceptionState& exceptionState)
     {
         return anonymousNamedSetter(String::number(index), value, exceptionState);
     }
     bool anonymousIndexedDeleter(uint32_t index, ExceptionState& exceptionState)
     {
-        return anonymousNamedDeleter(AtomicString(String::number(index)), exceptionState);
+        return anonymousNamedDeleter(AtomicString::number(index), exceptionState);
     }
 
     virtual Element* element() = 0;
 
 protected:
     DOMStringMap()
     {
         ScriptWrappable::init(this);
     }
 };
 
 } // namespace WebCore
 
 #endif // DOMStringMap_h