Fix websocket client already closed raise error does not match
Fix websocket client already closed raise error does not match

As doc says "If the stream is closed, raises WebSocketClosedError"

lilydjwg/tornado,lilydjwg/tornado,tornadoweb/tornado,tornadoweb/tornado,lilydjwg/tornado,tornadoweb/tornado,tornadoweb/tornado,lilydjwg/tornado