combo-box-menu-item: Propagate pseudo classes to the combo menu

combo-box-menu-item: Propagate pseudo classes to the combo menu

ComboBoxMenuItems use ClutterClones to reconstruct the active item
in the associated ComboMenu, so pseudo class changes due to state
changes of the ComboBoxMenuItem don't have the intended effect
(since the actual style information is taken from the associated
ComboBoxMenu item).
As a fix, propagate relevant pseudo class changes to the active
ComboBoxMenu item.

https://bugzilla.gnome.org/show_bug.cgi?id=662799