Respect #[repr(transparent)]

[RReverser]

Describe the Bug

I'm not 100% sure whether this is a bug or a feature request, but, in theory, wasm-bindgen ABI can be seen as any other, and so repr(...) should have an effect.

Steps to Reproduce

1. Define a struct with a single field (or a single field and a zero-size type like PhantomData).
2. Add #[repr(transparent)] to signify that its ABI should be the same as the inner field.
3. Add #[wasm_bindgen] attribute to export struct to JS.

Expected Behavior

Struct is represented on the JS side as a type alias to the inner field.

Actual Behavior

A wrapper class is generated.

[nasso]

I'd like to work on that one :)