Support autofocus for amp-form

[sachiyos]

There is a request on Stack Overflow to add autofocus for amp-form. It'd be great if we could add autofocus support for amp-form.

[mkhatib]

Can you explain some more and maybe link to the stack overflow question?

Is this autofocus for inputs? What's the use case?

[sachiyos]

Yes, I meant the autofocus for inputs. The stackoverflow post (http://stackoverflow.com/questions/39771830/is-it-possible-to-have-callback-for-amp-lightbox) requests the autofocus for amp-lightbox. It'd be nice to have autofocus for inputs for these components, that require inputs from users.

[ericlindley-g]

Got it—thanks @sachiyos ! I think we can consider this a feature request to trigger auto-focus on opening <amp-lightbox>, with the specific use-case of focusing on a form input.

Might be a good thing to enable during a larger overhaul into <amp-modal>?

[aghassemi]

Closing as dup of #7626