WebKit attempts to use geoclue D-Bus APIs from the web process, but this is not allowed by the bubblewrap sandbox. BubblewrapLauncher could easily allow access to geoclue D-Bus APIs, but we should not do that. The proper fix is to talk to the geolocation portal instead of attempting to use geoclue directly. This could be solved at the same time as bug #218121.
I'm wrong, Adrian points out that geoclue is only accessed from the UI process. I think something else is wrong with my geoclue.