Motivation:
Netty will fail a handshake for the Per-Message Deflate WebSocket
extension if the server response contains a smaller
`server_max_window_bits` value than the client offered.
However, this is allowed by RFC 7692:
> A server accepts an extension negotiation offer with this parameter
> by including the “server_max_window_bits” extension parameter in the
> extension negotiation response to send back to the client with the
> same or smaller value as the offer.
Modifications:
- Allow the server to respond with a smaller value than offered.
- Change the unit tests to test for this.
Result:
The client will not fail when the server indicates it is using a
smaller window size than offered by the client.
f1742c0e43