Safari Desktop: Doesn't fire inputType 'formatBold', 'formatItalic' etc. in beforeinput

It works just fine on Safari Mobile and the other desktop browsers. I think this is an oversight and should be fixed.

Then in my editor lib (https://svedit.dev) I could drop the redundant keydown handlers, and everything runs via beforeinput.

Repro: https://w3c.github.io/editing/repros/492.html