search-one-offs.js reads and writes popup.selectedIndex a bunch of times. UrlbarView doesn't currently have a selectedIndex property.

It would be good if we could update UrlbarTestUtils to use this as well:

https://searchfox.org/mozilla-central/rev/152993fa346c8fd9296e4cd6622234a664f53341/browser/components/urlbar/tests/UrlbarTestUtils.jsm#282

Does it make sense to have selectedIndex? Suppose that we have 2 groups of results side by side, one on the left and one on the right, and one-off buttons below or above everything... what is selectedIndex in that case?

Note, we could also keep the concept of selectedIndex and consider side by side groups as a continuation, so the first group is 1-10, the second one is 11-20... and so on. One-off buttons would also be a group by themselves and have their selectedIndex.
The only problematic case may be LTR vs RTL if the groups are inverted horizontally.

Note: browser_urlbarOneOffs_settings.js is ported but currently has test_open_settings_with_enter turned off, so we should look to enable that here when we implement/resolve this.

https://hg.mozilla.org/mozilla-central/rev/99ec4f94c2fe