Refocus after load completes failing.

[nathanhammond]

@BrennanRoberts reports that focus state is not successfully re-triggered when moving out of a loading state and into the desired content for a particular outlet. This issue appears to only affect Chrome/(Blink?).

• The element is blurred here.
• The element is focused here.

This happens synchronously, so it's possible that Blink doesn't support that behavior.

We should test a few options:

• Pushing the focus set onto the microtask queue. (Promise.resolve().then(() => { this.scrollPositionFocus(); }))
• Pushing the focus set onto the macrotask queue. (setTimeout(() => { this.scrollPositionFocus(); }, 0);)
• Pushing the focus set into a future backburner queue flush. (Ember.run.next(this, 'scrollPositionFocus');)

We would of course need to make sure that the async strategy still worked as expected with regards to Ember lifecycle and we did not break other browser/AT combinations.

Reproduction:
https://github.com/BrennanRoberts/ember-a11y-loading-focus-test-case

[BrennanRoberts]

Thanks for the suggestions, I'll look into this.