Remove unused code from MenuSelectWidget
Remove unused code from MenuSelectWidget

This is unused since Iab6e70c. It looks like it was forgotten
because the IDE didn't mark it as unused. But it is.

Change-Id: I7e90644d639f0d68372a9313f5af0ba51464b34a

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui