Allow web-sys to emit correct typescript declarations from webidl

[bennetthardwick]

This change adds the NamedAnyref adapter-type / descriptor, which behaves the same as an Anyref but also contains some information about the name. This allows web-sys to output the correct names for types instead of falling back to any.

If this feature is the kind of thing that the rustwasm team would like to merge - I'll make sure it's test covered. At the moment I just wanted to get it working and make sure it's something worth working on.

This is currently a breaking change but could be hidden behind a feature flag in web-sys.

[Pauan]

I don't think we should be worrying too much about TypeScript breaking changes, since TypeScript's type system is so loose, and it's always possible for people to use as to arbitrarily convert from one type to another.

[bennetthardwick]

That makes sense 👍 My only concern that was since the types were any before, there's a high chance that existing projects have been providing the wrong types, but it sounds like that's not too bad.

[alexcrichton]

Thanks for this! Could this be sure to add some tests as well to exercise it and ensure it works?

[bennetthardwick]

Hey @alexcrichton, I've added a few typescript tests. I couldn't find anywhere that explicitly tests stuff like ast::ImportKind through adapter2ts, so I figured just making some in the typescript-tests crate would be best.

Also since all of the webidl stuff is using this, the webidl-tests crate is making sure that it all works (at least in terms of wasm).

Please let me know if there's anywhere else I should write some tests 😄

[alexcrichton]

Looks great to me, thanks!