Closing popup always focuses the feature closest to the center

[Malvoz]

Closing a popup focuses the feature in the center as opposed to the corresponding feature of that popup (due to #596?).

https://maps4html.org/experiments/screenreader/restaurants/:

1. Tab (three times) to the Phucket Royal marker
2. Press Enter or Space to open popup
3. Press Esc to close popup

Expectation:
Phucket Royal marker is focused.

Result:
Sushi 88 marker is focused.