Fix for TimePicker not redrawing itself.

The problem was that NumberPicker override View.draw(), but did not
call the superclass version of the method in some situations. This
resulted in the DIRTY flag for the view not getting cleared properly,
and future invalidations not propagating correctly.

The fix was to call super.draw() from NumberPicker.draw().

Change-Id: Ic17215dea86d54b77375494ada124dd6970e3ad6