Stop using setAttribute for ARIA

[avelad]

Related to: #3378

[avelad]

I have reviewed the code and there are no more references. It is up to @joeyparrish to decide if the associated issue can be closed or not.

[theodab]

I just looked it up and... unfortunately, according to MDN, Firefox does not yet implement the ARIAMixin interface mixin. See: https://developer.mozilla.org/en-US/docs/Web/API/Element
I tried using ariaSelected on Firefox to confirm, and it does appear to be the case that these don't work.

So I don't know if we can actually use this yet. I've done some searching, but I couldn't find any talk about when or if Mozilla plans to implement ARIAMixin.

I suppose we could make an ARIAMixin polyfill, which uses Object.defineProperty to add getters and setters for the various values? We've been considering trying to reduce our reliance on polyfills, though, so this might not be a good time to add a new one.

[avelad]

I suppose we could make an ARIAMixin polyfill, which uses Object.defineProperty to add getters and setters for the various values? We've been considering trying to reduce our reliance on polyfills, though, so this might not be a good time to add a new one.

@theodab I'm bad at doing this kind of polyfills, could you help me with this?

[theodab]

I suppose we could make an ARIAMixin polyfill, which uses Object.defineProperty to add getters and setters for the various values? We've been considering trying to reduce our reliance on polyfills, though, so this might not be a good time to add a new one.

@theodab I'm bad at doing this kind of polyfills, could you help me with this?

Okay, I'll write a CL for that real fast. I'll update here when it has passed review.

[shaka-bot]

All tests passed!

[theodab]

Okay, the polyfill CL has passed review. I might as well merge now, as the lack of a polyfill was my last issue with this.
Thank you for your contributions!