Introduce HTMLDataListOptionsCollection subclass for HTMLCollection

Source/core/html/HTMLDataListElement.h

 /*
  * Copyright (c) 2009, Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 14 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef HTMLDataListElement_h
 #define HTMLDataListElement_h
 
-#include "core/html/HTMLCollection.h"
 #include "core/html/HTMLElement.h"
 
 namespace blink {
 
+class HTMLDataListOptionsCollection;
+
 class HTMLDataListElement FINAL : public HTMLElement {
 public:
     static PassRefPtrWillBeRawPtr<HTMLDataListElement> create(Document&);
 
-    PassRefPtrWillBeRawPtr<HTMLCollection> options();
+    PassRefPtrWillBeRawPtr<HTMLDataListOptionsCollection> options();
 
     void optionElementChildrenChanged();
 
 private:
     HTMLDataListElement(Document&);
     virtual void childrenChanged(const ChildrenChange&) OVERRIDE;
     virtual void finishParsingChildren() OVERRIDE;
 };
 
 } // namespace blink
 
 #endif // HTMLDataListElement_h