In order to implement enumerators with sizes, we have a SizeFn interface we implement for various types of collection and enumeration. However this interface currently only receives IRubyObject[] which means the runtime, context, self, and other contextual values must be captured (usually as an anonymous inner class) or acquired (e.g. runtime.getCurrentContext()).

This interface should be expanded to accept at least context and self, and all uses should be audited to see if we can make the impls static instances rather than creating them anew each time.