Flush in TWebSocketTransport pushes callbacks twice if transport is open

   flush: function(async, callback) {
      var self = this;
      if (this.isOpen()) {
        //Send data and register a callback to invoke the client callback
        this.socket.send(this.send_buf);
        this.callbacks.push((function() {
          var clientCallback = callback;
          return function(msg) {
            self.setRecvBuffer(msg);
            clientCallback();
          };
        }()));
        // Here the callback gets pushed a second time.
        if(callback) { // What is the intention of this code section?
          this.callbacks.push((function() {
            var clientCallback = callback;
            return function(msg) {
              self.setRecvBuffer(msg);
              clientCallback();
            };
          }()));
        }
      } else {
        //Queue the send to go out __onOpen
        this.send_pending.push({
          buf: this.send_buf,
          cb: callback
        });
      }
    }