setAttributeNode() does not properly normalize case.

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 64 matching lines @@
 #endif
 
     QualifiedName(const QualifiedName& other) : m_impl(other.m_impl) { ref(); }
     const QualifiedName& operator=(const QualifiedName& other) { other.ref(); deref(); m_impl = other.m_impl; return *this; }
 
     bool operator==(const QualifiedName& other) const { return m_impl == other.m_impl; }
     bool operator!=(const QualifiedName& other) const { return !(*this == other); }
 
     bool matches(const QualifiedName& other) const { return m_impl == other.m_impl || (localName() == other.localName() && namespaceURI() == other.namespaceURI()); }
 
+    bool matchesPossiblyIgnoringCase(const QualifiedName& other, bool shouldIgnoreCase) const { return m_impl == other.m_impl || (equalPossiblyIgnoringCase(localName(), other.localName(), shouldIgnoreCase) && namespaceURI() == other.namespaceURI()); }
+
     bool hasPrefix() const { return m_impl->m_prefix != nullAtom; }
     void setPrefix(const AtomicString& prefix) { *this = QualifiedName(prefix, localName(), namespaceURI()); }
 
     const AtomicString& prefix() const { return m_impl->m_prefix; }
     const AtomicString& localName() const { return m_impl->m_localName; }
     const AtomicString& namespaceURI() const { return m_impl->m_namespace; }
 
     // Uppercased localName, cached for efficiency
     const AtomicString& localNameUpper() const;
 
@@ skipping 59 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