BarToolGroup: Remove obsolete CSS selectors
BarToolGroup: Remove obsolete CSS selectors

Identified with help of local UnCSS installation, there are no
more icons and labels as direct children in BarToolGroup.

Change-Id: Ic18b0cc37c8d581eaff66431a0907a76802d781e

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