Fix bug where WebSocket's close wasn't sent to client

[edvakf]

At the moment, gate keeps holding the connection when the server closes a WebSocket connection through gate. Therefore, onclose of JavaScript's WebSocket object never gets called.

To be honest, I'm not too sure why this patch solves the problem... but I got it from studying another WebSocket proxy.

https://github.com/joinmytalk/drunken-hipster/blob/master/main.go#L49-L65

[typester]

Can you provide some html+javascript samples that reproduce this issue?

[edvakf]

An echo server example.

https://github.com/edvakf/go-websocket-sample

go run main.go

Type "bye" and hit enter to make the server close the connection.