Replace WTF::emptyString{16Bit}() with a static global

third_party/WebKit/Source/core/dom/DOMURLUtilsReadOnly.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 2012 Motorola Mobility Inc.
  *
  * 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.
@@ skipping 38 matching lines @@
     return kurl.host();
   if (isDefaultPortForProtocol(kurl.port(), kurl.protocol()))
     return kurl.host();
   return kurl.host() + ":" + String::number(kurl.port());
 }
 
 String DOMURLUtilsReadOnly::port(const KURL& kurl) {
   if (kurl.hasPort())
     return String::number(kurl.port());
 
-  return emptyString();
+  return emptyString;
 }
 
 String DOMURLUtilsReadOnly::search(const KURL& kurl) {
   String query = kurl.query();
-  return query.isEmpty() ? emptyString() : "?" + query;
+  return query.isEmpty() ? emptyString : "?" + query;
 }
 
 String DOMURLUtilsReadOnly::hash(const KURL& kurl) {
   String fragmentIdentifier = kurl.fragmentIdentifier();
   if (fragmentIdentifier.isEmpty())
-    return emptyString();
+    return emptyString;
   return AtomicString(String("#" + fragmentIdentifier));
 }
 
 }  // namespace blink