Would it be possible/reasonable/desired to support a wasm32-unknown-unknown backend without needing to use emscripten? I'm a little inspired by this crate: https://github.com/ryanisaacg/quicksilver which does it by providing a Javascript interface and it seems to work okay, though I don't know what invariants winit needs to provide that wasm32-unknown-unknown might make hard (mainloop callback, presence of threads, etc).