Make it obvious an HTMLOptionsCollection can only contain HTMLOptionElements

Source/core/html/HTMLOptionsCollection.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef HTMLOptionsCollection_h
 #define HTMLOptionsCollection_h
 
 #include "core/html/HTMLCollection.h"
+#include "core/html/HTMLOptionElement.h"
 
 namespace blink {
 
 class ExceptionState;
-class HTMLOptionElement;
-class HTMLSelectElement;
 
 class HTMLOptionsCollection FINAL : public HTMLCollection {
 public:
     static PassRefPtrWillBeRawPtr<HTMLOptionsCollection> create(ContainerNode&, CollectionType);
 
+    HTMLOptionElement* item(unsigned offset) const { return toHTMLOptionElement(HTMLCollection::item(offset)); }
+
     void add(PassRefPtrWillBeRawPtr<HTMLOptionElement>, ExceptionState&);
     void add(PassRefPtrWillBeRawPtr<HTMLOptionElement>, int index, ExceptionState&);
     void remove(int index);
 
     int selectedIndex() const;
     void setSelectedIndex(int);
 
     void setLength(unsigned, ExceptionState&);
     void namedGetter(const AtomicString& name, RefPtrWillBeRawPtr<NodeList>&, RefPtrWillBeRawPtr<Element>&);
     bool anonymousIndexedSetter(unsigned, PassRefPtrWillBeRawPtr<HTMLOptionElement>, ExceptionState&);
 
+    bool elementMatches(const HTMLElement&) const;
+
 private:
     explicit HTMLOptionsCollection(ContainerNode&);
 
     virtual void supportedPropertyNames(Vector<String>& names) OVERRIDE;
 };
 
 DEFINE_TYPE_CASTS(HTMLOptionsCollection, LiveNodeListBase, collection, collection->type() == SelectOptions, collection.type() == SelectOptions);
 
+inline bool HTMLOptionsCollection::elementMatches(const HTMLElement& element) const
+{
+    return isHTMLOptionElement(element);
+}
+
 } //namespace
 
 #endif