GitLab

Until we have inline installation (#14936) enabled we have to do that.

This is an heavy adaptation of Giorgio's code but it adapts the display
logic to the new page and also makes it more explicit.

Note that I'm taking for granted here that there will be a Chrome
version at the same time as a Firefox version which is not sure yet.

This reverts commit 487b1488.

This method won't work with our URL layout. We should use an HTML tag
instead.

Signed on AMO and self-distributed: it won't be publicly listed on AMO
and won't have to go through their employees review.

The extension sets a custom data attribute when the extension is
installed or updated but I don't know how to listen to that change with
JavaScript so unfortunately, I'm encoding this logic in CSS for now.

This is only an expiry date bump.