Introduce HasHTMLTagName functor and use it with ElementTraversal

Source/core/html/HTMLElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004-2007, 2009, 2014 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.
  *
@@ skipping 131 matching lines @@
 {
     ASSERT(!tagName.localName().isNull());
     ScriptWrappable::init(this);
 }
 
 inline bool Node::hasTagName(const HTMLQualifiedName& name) const
 {
     return isHTMLElement() && toHTMLElement(*this).hasTagName(name);
 }
 
+// Functor used to match HTMLElements with a specific HTML tag when using the ElementTraversal API.
+class HasHTMLTagName {
+public:
+    explicit HasHTMLTagName(const HTMLQualifiedName& tagName): m_tagName(tagName) { }
+    bool operator() (const HTMLElement& element) const { return element.hasTagName(m_tagName); }
+private:
+    const HTMLQualifiedName& m_tagName;
+};
+
 // This requires isHTML*Element(const Element&) and isHTML*Element(const HTMLElement&).
 // When the input element is an HTMLElement, we don't need to check the namespace URI, just the local name.
 #define DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(thisType) \
     inline bool is##thisType(const thisType* element); \
     inline bool is##thisType(const thisType& element); \
     inline bool is##thisType(const HTMLElement* element) { return element && is##thisType(*element); } \
     inline bool is##thisType(const Node& node) { return node.isHTMLElement() ? is##thisType(toHTMLElement(node)) : false; } \
     inline bool is##thisType(const Node* node) { return node && is##thisType(*node); } \
     inline bool is##thisType(const Element* element) { return element && is##thisType(*element); } \
     template<typename T> inline bool is##thisType(const PassRefPtr<T>& node) { return is##thisType(node.get()); } \
     template<typename T> inline bool is##thisType(const RefPtr<T>& node) { return is##thisType(node.get()); } \
     template <> inline bool isElementOfType<const thisType>(const HTMLElement& element) { return is##thisType(element); } \
     DEFINE_ELEMENT_TYPE_CASTS_WITH_FUNCTION(thisType)
 
 } // namespace blink
 
 #include "core/HTMLElementTypeHelpers.h"
 
 #endif // HTMLElement_h