Fix #TabsToolbar's bottom border (#37)
Fix #TabsToolbar's bottom border (#37)

lbrfabio/firefox-gnome-flat,gnome-integration-team/firefox-gnome,synapsos/firefox-gnome,gnome-integration-team/firefox-gnome,synapsos/firefox-gnome,lbrfabio/firefox-gnome-flat,lbrfabio/firefox-gnome-flat,gnome-integration-team/firefox-gnome,synapsos/firefox-gnome,gnome-integration-team/firefox-gnome,lbrfabio/firefox-gnome-flat,synapsos/firefox-gnome