Adding options parameter to caretPositionFromPoint

[captainbrosset]

Here's the caretPositionFromPoint feature: explorer, source file.

It's supported in Chrome, Edge, and Firefox. And has actually been supported in Firefox for many years.

There's one more BCD key that belongs to this feature: api.Document.caretPositionFromPoint.options_parameter.

But, adding it to the feature would demote Firefox to non supporting. Firefox doesn't yet support the options param, but they're adding it in https://bugzilla.mozilla.org/show_bug.cgi?id=1914596 and might complete this as part of interop 25 so, optimistically, this year.

Adding it to the feature and demoting Firefox doesn't feel fair since Firefox has had the API for many years. But not adding it feels wrong too. Adding it behind a compute_from statement doesn't feel right either since that options param allows usage across shadow dom, which is a big deal.

I think we should either create a new feature just for the shadow dom usage of the function, or wait for Firefox to ship the option.