    } else if (focused) {
        cls += ' is-highlighted'
      }
      return cls;
    },

    _computeAddOnContentClass: function(focused, invalid) {
      var cls = 'add-on-content';
      if (invalid) {
        cls += ' is-invalid';
      } else if (focused) {
        cls += ' is-highlighted'
      }
      return cls;
    }
  });
</script>
