After #39812 it seems that API unit tests are not running at all (though they look like they are). In the meantime, it seems that test_theme_change regressed and now fails with this:

 stderr ───

    thread 'test_theme_change' panicked at components/servo/tests/webview.rs:147:5:
    assertion `left == right` failed
      left: Ok(Boolean(false))
     right: Ok(Boolean(true))

The theme is not reported as being the dark theme. The problem here seems to be that the Device is not updated until we restyle and none evaluating the match media does not trigger a restyle and Device update.