Review use of abortSignal in events listener patterns.

[Westbrook]

Code of conduct

• I agree to follow this project's code of conduct.

Description of issue

Can whatwg/dom#911 be leveraged along the lines of:

const ac = new AbortController();
let { signal } = ac;
parentElement.addEventListener(
    'pointerenter',
    this.openOverlay,
    { signal }
);
parentElement.addEventListener('focusin', this.openOverlay, { signal });
parentElement.addEventListener(
    'pointerleave',
    this.closeOverlay,
    { signal }
);
parentElement.addEventListener('focusout', this.closeOverlay, { signal });
ac.abort();

To simplify events being added/removed from elements imperatively.

Things to confirm:

• does the abortController really work across multiple listeners?
• does Safari support it broadly enough to allow in the library?
• does it have undesired perf costs?
• others?