Autofocus test port

[domenic]

Supercedes #9440.

@annevk, I am hoping you and @tkent-google can be my review-buddies for these things.

This test fails in Firefox and Safari:

• Firefox does not move focus from the div. That seems bad.
• Safari puts focus on the body. I have no idea why it would do that.

I think of the three behaviors, the spec/Chrome behavior is the most reasonable, so I'd like to merge this and file bugs. Let me know if folks disagree. /cc @smaug---- @cdumez.

[domenic]

Ah, buttons are just not programmatically focusable in Safari. I will use textboxes.

Edit: that doesn't make a difference; Safari still doesn't autofocus. They seem to fail a lot of sibling web platform tests...

[domenic]

Filed https://bugs.webkit.org/show_bug.cgi?id=197794 for the Safari not firing select bug (the prequisite test here). I'll hold off on filing autofocus bugs until we have more eyes on the test.

[tkent-google]

• Firefox does not move focus from the div. That seems bad.

Firefox might think the explicit focus() for the div matches to the following condition in the specification though it's not a user indication.
IMO Firefox's behavior is understandable. Ignoring autofocus would be safer because the focus() might have been executed by a user indication.

1. If the user has indicated (for example, by starting to type in a form control) that they do not wish focus to be changed, then optionally return.

I know Firefox also ignores autofocus if the page is loaded with a fragment. crbug.com/382901

[domenic]

@annevk, maybe @smaug----, what do you think we should do here? I guess the "optionally return" steps, by a strict reading, make most testing of autofocus="" impossible.

[tkent-google]

I filed a specification issue: whatwg/html#4645

[domenic]

Overtaken by whatwg/html#4763 and associated test PR.