DraggableElement: Remove 'HACK' comment, this isn't a hack
DraggableElement: Remove 'HACK' comment, this isn't a hack

It's just everything being horrible, as usual.

Change-Id: I630be1c290724d835815eba393689f556b20133f

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