XXX A good XPointerResult would probably mimic XPathresult,
     this range list is just the minimum that will be able to represent
     all return values, although it would be more user friendly to return
     nodes and node lists when they are possible.
[scriptable, uuid(d3992637-f474-4b65-83ed-323fe69c60d2)]
interface nsIXPointerResult : nsISupports


readonly attribute unsigned long length


nsIDOMRange item(in unsigned long index)