Add interactivity:inert focus() test
Test that focus() does not work for input in interactivity:inert. Also
test that flipping back to interactivity:auto in an inert subtree allows
focusing again.
Also modified test not tentative and still referring to visibility.
Bug: 370065759
Change-Id: I0a7d592f85566e550ef04028e7e0d734c831166a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5993677
Reviewed-by: Daniil Sakhapov sakhapov@chromium.org
Commit-Queue: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1378872}