Introduce LiteralSet

Source/core/dom/QualifiedName.h

 /*
  * 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 105 matching lines @@
 inline const QualifiedName& anyQName() { return anyName; }
 #endif
 
 const QualifiedName& nullQName();
 
 inline bool operator==(const AtomicString& a, const QualifiedName& q) { return a == q.localName(); }
 inline bool operator!=(const AtomicString& a, const QualifiedName& q) { return a != q.localName(); }
 inline bool operator==(const QualifiedName& q, const AtomicString& a) { return a == q.localName(); }
 inline bool operator!=(const QualifiedName& q, const AtomicString& a) { return a != q.localName(); }
 
+// Useful with TableSet.
+bool lessThanByImplAddress(const QualifiedName* const&, const QualifiedName* const&);

[eseidel, 2013/05/22 00:40:14]

I think these probably belong as static class methods on QualifiedName.  Or
traits-style?  traits might be cleaner.  Up to you.  Free methods don't make
much sense to me though.

+bool lessThanByLocalNameImplAddress(const QualifiedName* const&, const QualifiedName* const&);
+
 inline unsigned hashComponents(const QualifiedNameComponents& buf)
 {
     return StringHasher::hashMemory<sizeof(QualifiedNameComponents)>(&buf);
 }
 
 struct QualifiedNameHash {
     static unsigned hash(const QualifiedName& name) { return hash(name.impl()); }
 
     static unsigned hash(const QualifiedName::QualifiedNameImpl* name) 
     {
@@ skipping 21 matching lines @@
         typedef WebCore::QualifiedNameHash Hash;
     };
     
     template<> struct HashTraits<WebCore::QualifiedName> : SimpleClassHashTraits<WebCore::QualifiedName> {
         static const bool emptyValueIsZero = false;
         static WebCore::QualifiedName emptyValue() { return WebCore::nullQName(); }
     };
 }
 
 #endif