[w3c/ServiceWorker] Expose the Fetch Metadata Request Headers (#1513)

Currently the headers for a service-worker request don't contain any of the `Sec-*` values.

[`Sec-Fetch-Dest`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Dest) & [`Sec-Fetch-Mode`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Mode) are the interesting ones.

**Use case: Injecting code into web workers**

Currently it's impossible to tell if request is going to be loaded as a web worker, without checking against a hardcoded path.

With the `Sec-Fetch-Dest` header, you're able to differentiate between code loaded as a worker, or script.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/ServiceWorker/issues/1513