message: add data-arg attribute for more complex args
diff: @@ -298,9 +298,10 @@ export default class ListenerGenerator
  });
  this._attachValidatorEvent();
  - if (this.binding.arg) {
  - this.unwatch = this.vm.$watch(this.binding.arg, (value) => {
  - this.vm.$validator.validate(this.binding.arg, value, getScope(this.el));
  + const arg = this.binding.arg || getDataAttribute(this.el, 'arg');
  + if (arg) {
  + this.unwatch = this.vm.$watch(arg, (value) => {
  + this.vm.$validator.validate(this.fieldName, value, getScope(this.el));
  });
  return;
  