Support for async generators

[egriff38]

Hello,
I was wondering how feasable it would be to add async generator support to web workers? I think using async function* and for await() would be an absolutely astounding way to utilized workers as streams rather than just one-off async functions. The hardest part I would imagine would be facilitating the connection between a specific generator instance in the worker vs the main thread.

[developit]

Just a note - comlink-loader is available and handles async generators in addition to most other interfaces. It's API is pretty similar to this loader.

[egriff38]

Looks great. Thanks!