Use Facebook Share dialog for Facebook invites on mobile. (#2409)
Use Facebook Share dialog for Facebook invites on mobile. (#2409)

Facebook's Send Message is desktop only, and shows an error
message on mobile browsers.  (It also doesn't have a reasonable
mobile UI.)  The Share dialog doesn't support sending private
messages on mobile, so we'll stick with Send Message on desktop.

Fixes https://github.com/uProxy/uproxy/issues/2121
jpevarnek/uproxy,uProxy/uproxy,uProxy/uproxy,uProxy/uproxy,jpevarnek/uproxy,jpevarnek/uproxy,jpevarnek/uproxy,uProxy/uproxy,jpevarnek/uproxy,uProxy/uproxy