Geolocation permission policy tests are wrong

https://github.com/web-platform-tests/wpt/blob/master/geolocation/disabled-by-permissions-policy.https.sub.html and it's friends.

First it needs to wait for the iframe to be fully active, and it also should grant permission to the iframe, otherwise it'll fail regardless of the permission policy.

@marcoscaceres You are touching Geolocation nowadays, are you interested?