revert: "websocket: pre-calculated length"

[KhafraDev]

This reverts 13523fd which broke permessage-deflate support.

See #3289 for why the tests did not catch this.

Can you add a test to avoid further regressions?

The tests catch it already, it's just that the Autobahn workflow doesn't quite work as expected and it uses a previous commit rather than the current one. Once the issue linked is resolved it'll be fixed.

The tests in #3283 are failing because of this, or you can see the first comment that the bot made before the edit. There is a lot broken right now I'd appreciate if we could land this in the meantime.

@mcollina
Please remove your blocking review.

@KhafraDev
Is it normal that the autobahn workflow is so slow?

Yes, you have to understand that these tests send GB of frames over that need to parsed and mirrored to the server. The longer the tests, the more likely the tests are to succeed because the server will instantly fail/close the connection if it receives something unexpected.

Ah, ok. ;)

the autobahn workflow runs tests that detected this regression originally

cc @tsctx I'm pretty positive that the issue came with the custom Buffer.concat.