Motivation:
RFC 6455 defines that, generally, a WebSocket client should not close a TCP
connection as far as a server is the one who's responsible for doing that.
In practice tho', it's not always possible to control the server. Server's
misbehavior may lead to connections being leaked (if the server does not
comply with the RFC).
RFC 6455 #7.1.1 says
> In abnormal cases (such as not having received a TCP Close from the server
after a reasonable amount of time) a client MAY initiate the TCP Close.
Modifications:
* WebSocket client handshaker additional param `forceCloseAfterMillis`
* Use 10 seconds as default
Result:
WebSocket client handshaker to comply with RFC. Fixes#8883.
ee351ef8bc