Followup 6ede2d8: fix popup font size
Followup 6ede2d8: fix popup font size

The theme invocation for popupTool was run in the wrong
context (popupWidget rather than popupTool), so the theme's
font size rules weren't being applied.

Change-Id: I8a0a134a027b6843aff7941be62e597f50da7885

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