Match format names in https://www.iana.org/assignments/http-parameters/http-parameters.xhtml#content-coding

[ricea]

trafficstars

It would be good to explicitly match the format names in https://www.iana.org/assignments/http-parameters/http-parameters.xhtml#content-coding. Currently we implicitly match them, so it's not a big change.

It's unclear what to do about possible future formats that aren't used for HTTP.

[ricea]

This makes "deflate-raw" awkward. It's something we definitely want to support in future, but it's not used by HTTP, and almost certainly never will be.

[ylafon]

Note that you don't need to support all of them, just have the name of the supported compression format be the same as the ones listed there.