fetch() does not decompress gzip responses

[mattfysh]

fetch() appears to return the raw gzip-compressed response body instead of transparently decompressing it.

Minimal repro:

const res = await fetch('https://httpbin.org/gzip')

console.log(res.status)
console.log(res.headers.get('content-encoding'))
console.log(await res.text())

Observed:

200
gzip
<binary gzip data>

Expected:

200
gzip
{
  "gzipped": true,
  ...
}

Response.text() should expose the decompressed body.