impr: remove connection guards (@fehmer)

[fehmer]

We are using navigator.onLine to detect if the user is online. This is not very reliable and we get bug reports from people who are able to access the site but are prevented from logging in.

Browsers and operating systems leverage different heuristics to determine whether the device is online. In general, connection to LAN is considered online, even though the LAN may not have Internet access.
[...] On Windows, the online status is determined by whether it can reach a Microsoft home server, which may be blocked by firewalls or VPNs, even if the computer has Internet access.
Therefore, this property is inherently unreliable, and you should not disable features based on the online status, only provide hints when the user may seem offline.

source: mdn Navigator.onLine