There's two errors in IceCat:* The inbuild LibreJS add-on is blocking the login page: Menu -> Sign In To Sync... (about:accounts?action=signin&entrypoint=menubar). * IceCat 52.0.2 (but not Abrowser 52.0.2) have to be restarted for Edit -> Preferences -> Sync (about:preferences#sync) to show anything after you have logged in, or the page will be blank.
