Make the fields of RequestInit optional.

[zakpatterson]

This way, users do not have to recite every field when creating a RequestInit. Also, the spec says the RequestInit dictionary must contain a field window which is set to null. We might as well include this too as a final variable, since the spec shows omitting it should be a type error.

Prompted by gitter conversation here: https://gitter.im/scala-js/scala-js?at=5d80415105fd3716953afa47

[zakpatterson]

I see, however that @js.native traits are not supposed to have default definitions: https://www.scala-js.org/doc/interoperability/facade-types.html. Oddly this works with scala.js 1.0 and 0.6 on scala 2.12 and 2.13, but fails on 2.11 and 2[.yikes].10.

[flavomulti]

I think if you pull off the js.native this will work as expected though. Are you going to resubmit?

[zakpatterson]

@flavomulti I just removed the js.native as you suggested. I remember now that I added that so that the window field could be set to null explicitly. Perhaps the way I have it now will work?

[flavomulti]

I think that as long as its not set, e.g. js.undefined, its ok not to specify it. If you do specify window, it must be null...something like that. It's never clear why funky things like this exist, but it is what it is.

[zakpatterson]

Ah, that makes sense. So this will still throw a typeerror if a user tries to set it to something that's not null, which is what the spec wants. Ok thanks @flavomulti !

[aappddeevv]

Is there anyway to get this merged? With 1.0 out, we really need js.undefined on the RequestInit trait's properties as it is very unergonomic to use otherwise.

[sjrd]

Hi! Sorry for being so late in answering this. Thanks for the PR.

I just have one comment below:

[sjrd]

Thank you @zakpatterson

[aappddeevv]

Thanks!