This adds the test that ensures that the search focus is still
focused, even after the selection is updated (for whatever reason).
Note that we are not triggering the `change` event here, and are
instead just re-calling `update` on the selection adapter. This is
because we do not bind the `change` event in tests, so the selection
is never re-rendered and the tests will pass. The `update` method
is triggered during the `change` cycle anyway, so this has the
same effect while supporting cases where the selection is re-rendered
without the selected values changing.
