<details> element is tabbable via keyboard but has a computed tabIndex of -1

[giacomo-petri]

The <details> element remains focusable and operable via keyboard even when no <summary> is nested. Given this behavior, I would expect its computed tabIndex value to be 0. However, none of the major browsers expose it as such (all return -1).

I understand that WPT currently focuses on testing accessible names and roles, but considering there is an existing folder in WPT called "focus", it might be reasonable and feasible to include this scenario as well.

I've added a file in wpt/focus, but feel free to remove, update, or modify it if it's misplaced or if the approach is incorrect.

[rahimabdi]

Thank you @giacomo-petri.

Please see this related issue around adding keyboard testing utilities: #101.