websocket: remove redundant error handling

Change-Id: I1b0e8812ca5b2e3ca72948d5414d569879e54f35
Reviewed-on: https://go-review.googlesource.com/21461
Reviewed-by: Andrew Gerrand <adg@golang.org>

websocket/websocket.go

@@ -209,9 +209,6 @@ func (ws *Conn) Write(msg []byte) (n int, err error) {
 	}
 	n, err = w.Write(msg)
 	w.Close()
-	if err != nil {
-		return n, err
-	}
 	return n, err
 }