Clean up forward declarations in Source/core

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 153 matching lines @@
     static bool equal(const QualifiedName& a, const QualifiedName& b) { return a == b; }
     static bool equal(const QualifiedName::QualifiedNameImpl* a, const QualifiedName::QualifiedNameImpl* b) { return a == b; }
 
     static const bool safeToCompareToEmptyOrDeleted = false;
 };
 
 } // namespace blink
 
 namespace WTF {
 
-    template<typename T> struct DefaultHash;
-
     template<> struct DefaultHash<blink::QualifiedName> {
         typedef blink::QualifiedNameHash Hash;
     };
 
     template<> struct HashTraits<blink::QualifiedName> : SimpleClassHashTraits<blink::QualifiedName> {
         static const bool emptyValueIsZero = false;
         static blink::QualifiedName emptyValue() { return blink::QualifiedName::null(); }
     };
 }
 
 #endif