img attrs: srcset, currentSrc, sizes, referrerPolicy, decoding, loading

[toastal]

Prerequisites

• Before opening a pull request, please check the HTML standard (https://dom.spec.whatwg.org/). If it doesn't appear in this spec, it may be present in the spec for one of the other purescript-web projects. Although MDN is a great resource, it is not a suitable reference for this project.

Description

Adding missing attributes for HTMLImage
https://html.spec.whatwg.org/multipage/embedded-content.html#dom-img-currentsrc

It would be nice to include decode(), but since it returns a Promise and this project doesn't include Aff, I skipped it.

[garyb]

Thanks for adding these, but can we introduce sum types for all the stringy attributes that only actually have a set of acceptable values? CanPlayType in this repo would be an existing example of that.

[toastal]

I wouldn't disagree, but it seemed like a lot of the APIs exposed in this repo are just stringly-typed. Can do though.

[toastal]

I think referrer-policy may be out of scope as it refers to specs outside of HTML. Not really sure what's best @garyb. Though in going through the ADTs, I caught an error in crossOrigin.

[thomashoneyman]

This looks good to me, though I would appreciate another look from @garyb.

[thomashoneyman]

Suggested change

[garyb]

All seems reasonable to me! Thanks for adding those sums.