Introduce and use type casting functions for several HTMLCollection types

Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 363 matching lines @@
 }
 
 PassRefPtrWillBeRawPtr<HTMLCollection> HTMLSelectElement::selectedOptions()
 {
     updateListItemSelectedStates();
     return ensureCachedHTMLCollection(SelectedOptions);
 }
 
 PassRefPtrWillBeRawPtr<HTMLOptionsCollection> HTMLSelectElement::options()
 {
-    return static_cast<HTMLOptionsCollection*>(ensureCachedHTMLCollection(SelectOptions).get());
+    return toHTMLOptionsCollection(ensureCachedHTMLCollection(SelectOptions).get());
 }
 
 void HTMLSelectElement::updateListItemSelectedStates()
 {
     if (!m_shouldRecalcListItems)
         return;
     recalcListItems();
     setNeedsValidityCheck();
 }
 
@@ skipping 1263 matching lines @@
 
 void HTMLSelectElement::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_listItems);
 #endif
     HTMLFormControlElementWithState::trace(visitor);
 }
 
 } // namespace