Mark the AtomicString(const String&) constructor as explicit

Source/core/frame/Location.cpp

 /*
  * Copyright (C) 2008, 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
@@ skipping 225 matching lines @@
         return;
     if (protocolIsJavaScript(m_frame->document()->url()))
         return;
     m_frame->navigationScheduler().scheduleRefresh();
 }
 
 void Location::setLocation(const String& url, DOMWindow* activeWindow, DOMWindow* firstWindow)
 {
     ASSERT(m_frame);
     // We call findFrameForNavigation to handle the case of a seamless iframe correctly.
-    Frame* frame = m_frame->loader().findFrameForNavigation(String(), activeWindow->document());
+    Frame* frame = m_frame->loader().findFrameForNavigation(nullAtom, activeWindow->document());
     if (!frame)
         return;
     frame->domWindow()->setLocation(url, activeWindow, firstWindow);
 }
 
 } // namespace WebCore