Nothing about VLANs under
/interface/wifi (or wifiwave2 ... it's been renamed in 7.13). So the config gives you a number of wifi interfaces (probably named wifi1, wifi2, etc.).
Then under
/interface/bridge something like this:
/interface bridge
set [ find name=bridge ] vlan-filtering=yes
/interface/bridge/port
add bridge=bridge interface=wifi1 frame-types=admit-only-untagged-and-priority-tagged pvid=13
add bridge=bridge interface=wifi2 frame-types=admit-only-untagged-and-priority-tagged pvid=666
# ... and optionally, doesn't have to be set explicitly, ROS adds ports with pvid set to appropriate VLANs automatically
/interface/bridge/vlan
set [ find bridge=bridge vlan-id=13 ] untagged=wifi1
set [ find bridge=bridge vlan-id=666 ] untagged=wifi2
So nothing really special, simply treat wifi interfaces as access ports for appropriate VLANs, just like you'd do for ether ports. The vital thing is to have vlan-filterig enabled on bridge, otherwise this won't work.