function blur($event) {
    hasFocus = false;

    if (!noBlur) {
      ctrl.hidden = shouldHide();
      evalAttr('ngBlur', { $event: $event });
    } else if (angular.isObject($event)) {
      $event.stopImmediatePropagation();
    }
  }
Handles input blur event, determines if the dropdown should hide.
@param {Event=} $event