rm unnecessary constructor

Author: jimmywarting

lib/channel_model.js

@@ -270,10 +270,6 @@ Channel.prototype.prefetch = Channel.prototype.qos = function(count, global) {
 // its argument to signify 'nack'.
 
 class ConfirmChannel extends Channel {
-  constructor(connection) {
-    super(connection);
-  }
-
   publish(exchange, routingKey, content, options, cb) {
     this.pushConfirmCallback(cb);
     return Channel.prototype.publish.call(this, exchange, routingKey, content, options);