This is a continuation of  issue 691074  "WebSockets uses zlib deflate with windowBits = 8 and no zlib/gzip wrapper". During investigation of that issue we identified some testing gaps. Items to address:

1. Modify fuzzer to vary the window sizes it tests with.
2. Add a round-trip test with a window size of 8.
3. Create a sample frame with offsets > 255 and verify that decompression fails safely with server_max_window_bits=8
4. Compress some sample data with client_max_window_bits=8 and verify no offsets > 255 are created.

The last two are stretch goals as they are probably too much work to implement.