Don't emit interface mixins

[srujzs]

They should be added to the interfaces they are mixed into. This allows for external static members to use the right nominal type. This CL also adds some logic to handle name collisions between instance and static operations, which is now needed for exactly one pair of operations: Response.prototype.json and Response.json. Also enables asserts in the translator.

#56

[sigmundch]

Nice!

[kevmoo]

Uh. Doesn't this mean, in some cases, you won't be able to polymorph over similar types since they won't share a base type?

[kevmoo]

Uh. Doesn't this mean, in some cases, you won't be able to polymorph over similar types since they won't share a base type?

Like you won't be able to make a function that takes GenericTransformStream as a type...

[srujzs]

That's true, but that's intentional, since they're not supposed to be used as types.

https://webidl.spec.whatwg.org/#idl-interface-mixins

Note that unlike interfaces or dictionaries, interface mixins do not create types.

Do you have an example where they are that I overlooked? GenericTransformStream isn't used as a type in the IDL afaict. If they are used as types, then one option is to just move the static members to the mixing-in class and keep the instance members and mixin interface around.

[kevmoo]

Do you have an example where they are that I overlooked?

I can imagine places where writing helpers/extensions on the shared types could be nice. I mean, we can always go back to these later. This is ABSOLUTELY a breaking change, though.

...I mean, if folks are actually using these types already. 🤷‍♂️

[srujzs]

Searching GitHub gave me no results for these mixin types being used with package:web, but that isn't too surprising. I've added this change to the changelog, and if we change our minds later about wanting these types to be emitted, we can go the route of comment#5..