[selectors] :focus-visible matches on initial programmatic focus

• Spec: https://drafts.csswg.org/selectors/#the-focus-visible-pseudo

We have a test focus-visible-010.html that checks that a programmatic focus on the load event, causes that the element getting focused matches :focus-visible. This test passes in the 2 implementations of :focus-visible (Chromium and Firefox).

However the spec doesn't mention anything about this in the suggestions list, and given that 2 browsers follow that, and we have a test, maybe it'd be nice to add that to the list too.

The spec mentions 2 cases of programmatic focus:

• If the active element matches :focus-visible, and a script causes focus to move elsewhere, the newly focused element should match :focus-visible.
• Conversely, if the active element does not match :focus-visible, and a script causes focus to move elsewhere, the newly focused element should not match :focus-visible.

But it doesn't mention what happens when there's no active element before the programmatic focus. WDYT?

CC @alice @emilio

Read the Selectors specification's :focus-visible section and review the focus-visible-010.html test linked in the issue. Determine how initial programmatic focus should be described in the suggestions list, then confirm that the specification wording matches the tested behavior and the agreed resolution.