VisualEditorOverlay: Update for Idc299e23 in OOUI

Quote, "We may want to move these to an oojs-ui theme at some point".
That would indeed help. I had no idea there are styles overriding this here,
otherwise I would have submitted a fix for the breaking change.

Bug: T85025
Change-Id: Ic9a86a3342034c538933cda8b20f0dad62c38d42
Merge "VisualEditorOverlay: Update for Idc299e23 in OOUI"