Make HashTraits<QualifiedName>::emptyValue return a const reference

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

 /*
  * Copyright (C) 2005, 2006, 2009 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 102 matching lines @@
 DEFINE_GLOBAL(QualifiedName, nullName);
 
 void QualifiedName::initAndReserveCapacityForSize(unsigned size) {
   DCHECK(starAtom.impl());
   qualifiedNameCache().reserveCapacityForSize(size +
                                               2 /*starAtom and nullAtom */);
   new ((void*)&anyName) QualifiedName(nullAtom, starAtom, starAtom, true);
   new ((void*)&nullName) QualifiedName(nullAtom, nullAtom, nullAtom, true);
 }
 
-const QualifiedName& QualifiedName::null() {
-  return nullName;
-}
-
 const AtomicString& QualifiedName::localNameUpper() const {
   if (!m_impl->m_localNameUpper)
     m_impl->m_localNameUpper = m_impl->m_localName.upperASCII();
   return m_impl->m_localNameUpper;
 }
 
 unsigned QualifiedName::QualifiedNameImpl::computeHash() const {
   QualifiedNameComponents components = {m_prefix.impl(), m_localName.impl(),
                                         m_namespace.impl()};
   return hashComponents(components);
 }
 
 void QualifiedName::createStatic(void* targetAddress,
                                  StringImpl* name,
                                  const AtomicString& nameNamespace) {
   new (targetAddress)
       QualifiedName(nullAtom, AtomicString(name), nameNamespace, true);
 }
 
 void QualifiedName::createStatic(void* targetAddress, StringImpl* name) {
   new (targetAddress)
       QualifiedName(nullAtom, AtomicString(name), nullAtom, true);
 }
 
 }  // namespace blink