Introduce and use type casting functions for several HTMLCollection types

Source/core/dom/ClassCollection.h

 /*
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 David Smith (catfish.man@gmail.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 39 matching lines @@
 
     bool elementMatches(const Element&) const;
 
 private:
     ClassCollection(ContainerNode& rootNode, const AtomicString& classNames);
 
     SpaceSplitString m_classNames;
     AtomicString m_originalClassNames;
 };
 
+DEFINE_TYPE_CASTS(ClassCollection, LiveNodeListBase, collection, collection->type() == ClassCollectionType, collection.type() == ClassCollectionType);
+
 inline bool ClassCollection::elementMatches(const Element& testElement) const
 {
     if (!testElement.hasClass())
         return false;
     if (!m_classNames.size())
         return false;
     // FIXME: DOM4 allows getElementsByClassName to return non StyledElement.
     // https://bugs.webkit.org/show_bug.cgi?id=94718
     if (!testElement.isStyledElement())
         return false;
     return testElement.classNames().containsAll(m_classNames);
 }
 
 } // namespace WebCore
 
 #endif // ClassCollection_h