Enable WTF::HashSet<OwnPtr<> >

Source/wtf/HashTraits.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 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 126 matching lines @@
         static const bool emptyValueIsZero = true;
         static void constructDeletedValue(T& slot) { new (NotNull, &slot) T(HashTableDeletedValue); }
         static bool isDeletedValue(const T& value) { return value.isHashTableDeletedValue(); }
     };
 
     template<typename P> struct HashTraits<OwnPtr<P> > : SimpleClassHashTraits<OwnPtr<P> > {
         typedef std::nullptr_t EmptyValueType;
 
         static EmptyValueType emptyValue() { return nullptr; }
 
+        static const bool hasIsEmptyValueFunction = true;
+        static bool isEmptyValue(const OwnPtr<P>& value) { return !value; }
+
+        typedef typename OwnPtr<P>::PtrType PeekInType;
+
         typedef PassOwnPtr<P> PassInType;
         static void store(PassOwnPtr<P> value, OwnPtr<P>& storage) { storage = value; }
 
         typedef PassOwnPtr<P> PassOutType;
         static PassOwnPtr<P> passOut(OwnPtr<P>& value) { return value.release(); }
         static PassOwnPtr<P> passOut(std::nullptr_t) { return nullptr; }
 
         typedef typename OwnPtr<P>::PtrType PeekOutType;
         static PeekOutType peek(const OwnPtr<P>& value) { return value.get(); }
         static PeekOutType peek(std::nullptr_t) { return 0; }
@@ skipping 153 matching lines @@
     };
 
 } // namespace WTF
 
 using WTF::HashTraits;
 using WTF::PairHashTraits;
 using WTF::NullableHashTraits;
 using WTF::SimpleClassHashTraits;
 
 #endif // WTF_HashTraits_h