Do not open autoupdate connections in new invisible tabs

[bastianjoel]

With #2918 the inactivity timeout was disabled for unstable hidden tabs.

Without that fix the app would load for 5 minutes when the user opens a link in a new tab which is initially not visible and focuses it before the app is stable.

[rrenkert]

@bastianjoel is this still relevant?

[bastianjoel]

Yes.