Content-length behavior in Workers isn't documented

[vlovich]

Expected Behavior

The documentation should call out that the content-length header is ignored when constructing a custom response/request. To have it set correctly, the body must be an instance of FixedLengthStream.

Actual Behavior

FixedLengthStream is undocumented. The fact that content-length is ignored for custom streams isn't mentioned.

Section that requires update

Request Response TransformStream or as a separate page under Streams

[vlovich]

I assume forwarded requests/responses preserve the content-length. I assume a custom ReadableStream wrapping some custom underlying source doesn't work here & currently needs to be wrapped in FixedLengthStream. Probably a good idea to have examples on how to do this too.

[gregory]

OMG! I wasted so much time on this! Please update the doc 🙏