It is unclear if the algorithm for gamepadconnected event matches implementations

[smaug----]

https://w3c.github.io/gamepad/#event-gamepadconnected doesn't seem to check for example if the window is in background tab.
At least some implementations require foreground window.

[nondebug]

Allowing gamepad access from non-foreground windows is intentional, but perhaps we should check that the page is visible? The Chromium implementation requires visibility before events are dispatched.

On some platforms the system APIs we use to access gamepad inputs have focus requirements that prevent background access. Chromium uses a variety of APIs to access gamepads so sometimes this behavior can differ between different gamepads on the same system.