Make calls to AtomicString(const String&) explicit in web/

Source/core/html/HTMLBaseElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 54 matching lines @@
     HTMLElement::removedFrom(insertionPoint);
     if (insertionPoint->inDocument())
         document().processBaseElement();
 }
 
 bool HTMLBaseElement::isURLAttribute(const Attribute& attribute) const
 {
     return attribute.name().localName() == hrefAttr || HTMLElement::isURLAttribute(attribute);
 }
 
-String HTMLBaseElement::target() const
+AtomicString HTMLBaseElement::target() const
 {
     return fastGetAttribute(targetAttr);
 }
 
 KURL HTMLBaseElement::href() const
 {
     // This does not use the getURLAttribute function because that will resolve relative to the document's base URL;
     // base elements like this one can be used to set that base URL. Thus we need to resolve relative to the document's
     // URL and ignore the base URL.
 
@@ skipping 10 matching lines @@
 
     return url;
 }
 
 void HTMLBaseElement::setHref(const AtomicString& value)
 {
     setAttribute(hrefAttr, value);
 }
 
 }