backport fix for #2039

UTF8 should always be validated for websockets, regardless of the incoming
message type.

irc/ircconn.go

@@ -128,9 +128,9 @@ func (wc IRCWSConn) WriteLines(buffers [][]byte) (err error) {
 }
 
 func (wc IRCWSConn) ReadLine() (line []byte, err error) {
-	messageType, line, err := wc.conn.ReadMessage()
+	_, line, err = wc.conn.ReadMessage()
 	if err == nil {
-		if messageType == websocket.BinaryMessage && !utf8.Valid(line) {
+		if !utf8.Valid(line) {
 			return line, errInvalidUtf8
 		}
 		return line, nil