Consistently use AtomicString for namespaceURI / prefix

Source/bindings/v8/custom/V8CustomXPathNSResolver.h

 /*
  * Copyright (C) 2009 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 29 matching lines @@
 namespace WebCore {
 
 // V8CustomXPathNSResolver does not create a persistent handle to the
 // given resolver object.  So the lifetime of V8CustomXPathNSResolver
 // must not exceed the lifetime of the passed handle.
 class V8CustomXPathNSResolver : public XPathNSResolver {
 public:
     static PassRefPtr<V8CustomXPathNSResolver> create(v8::Handle<v8::Object> resolver, v8::Isolate*);
 
     virtual ~V8CustomXPathNSResolver();
-    virtual String lookupNamespaceURI(const String& prefix);
+    virtual AtomicString lookupNamespaceURI(const String& prefix) OVERRIDE;
 
 private:
     V8CustomXPathNSResolver(v8::Handle<v8::Object> resolver, v8::Isolate*);
 
     v8::Handle<v8::Object> m_resolver;  // Handle to resolver object.
     v8::Isolate* m_isolate;
 };
 
 } // namespace WebCore
 
 #endif  // V8CustomXPathNSResolver_h