Comment # 2 on bug 1108163 from Wolfgang Rosenauer

There is still code in Mozilla to work with dbus and NetworkManager apparently
to get surrounding access points for geolocation services.

Meanwhile found https://bugzilla.mozilla.org/show_bug.cgi?id=1179568 which
indicates that there is a new implementation covering the usecase in
netwerk/system/linux. From a very very quick look at it I'm not sure it does a
lot. It does not detect the online/offline status but instead watches out for
network change events to distribute them within Firefox.

So from all what I just found I would expect Firefox to behave correctly
already. At least that seems to be the intention.
Probably the exact scenario needs to be reported upstream to see where the
issue is.