Improve compatibility with wicg-inert

[ptrin]

When trying to use https://github.com/WICG/inert as the inert polyfill, I found that setting focus after closing the modal was not working because inert was not really removed yet when focus was being set. Here's a quote from the wing-inert README about the issue:

It relies on mutation observers to detect the addition of the inert
attribute, and to detect dynamically added content within inert subtrees.
Testing for inert-ness in any way immediately after either type of mutation
will therefore give inconsistent results; please allow the current task to end
before relying on mutation-related changes to take effect, for example via
setTimeout(fn, 0) or Promise.resolve().

[scottaohara]

so the only issue i have with this right now is that prior to this change, the script worked with IE11 out of the box.

can this be done in a way to avoid having to polyfill promise? or would the script need a new dependency like the promise polyfill?

[jfhector]

I think that setTimeout(fn, 0) should work.

The first answer to this Stack Overflow question explains what the technique does:
https://stackoverflow.com/questions/33955650/what-is-settimeout-doing-when-set-to-0-milliseconds/33955673

[scottaohara]

@ptrin, you wouldn't happen to have a chance to check this out again per my comment, would you?

[ptrin]

setTimeout looks like it works just as well, so thanks for the suggestion @jfhector :)