Shrink QualifiedNameImpl by 8 bytes on 64-bit platforms

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 16 matching lines @@
 #include "core/XLinkNames.h"
 #include "core/XMLNSNames.h"
 #include "core/XMLNames.h"
 #include "wtf/Assertions.h"
 #include "wtf/HashSet.h"
 #include "wtf/MainThread.h"
 #include "wtf/StaticConstructors.h"
 
 namespace blink {
 
+struct SameSizeAsQualifiedNameImpl : public RefCounted<SameSizeAsQualifiedNameImpl> {
+    unsigned bitfield;
+    void* pointers[4];
+};
+
+COMPILE_ASSERT(sizeof(QualifiedName::QualifiedNameImpl) == sizeof(SameSizeAsQualifiedNameImpl), qualified_name_impl_should_stay_small);
+
 static const int staticQualifiedNamesCount = HTMLNames::HTMLTagsCount + HTMLNames::HTMLAttrsCount
     + MathMLNames::MathMLTagsCount + MathMLNames::MathMLAttrsCount
     + SVGNames::SVGTagsCount + SVGNames::SVGAttrsCount
     + XLinkNames::XLinkAttrsCount
     + XMLNSNames::XMLNSAttrsCount
     + XMLNames::XMLAttrsCount;
 
 struct QualifiedNameHashTraits : public HashTraits<QualifiedName::QualifiedNameImpl*> {
     static const unsigned minimumTableSize = WTF::HashTableCapacityForSize<staticQualifiedNamesCount>::value;
 };
@@ skipping 89 matching lines @@
 {
     new (targetAddress) QualifiedName(nullAtom, AtomicString(name), nameNamespace, true);
 }
 
 void QualifiedName::createStatic(void* targetAddress, StringImpl* name)
 {
     new (targetAddress) QualifiedName(nullAtom, AtomicString(name), nullAtom, true);
 }
 
 }