function shouldStretchTabs () {
    switch (ctrl.stretchTabs) {
      case 'always':
        return true;
      case 'never':
        return false;
      default:
        return !ctrl.shouldPaginate
            && $window.matchMedia('(max-width: 600px)').matches;
    }
  }
Determines if the UI should stretch the tabs to fill the available space.
@returns {*}