message: Remove unused StateController.previousName
  Change-type: patch
diff: @@ -409,26 +409,11 @@ app.config(($locationProvider) => {
  app.controller('StateController', function ($rootScope, $scope) {
  const unregisterStateChange = $rootScope.$on('$stateChangeSuccess', (event, toState, toParams, fromState) => {
  - this.previousName = fromState.name
  this.currentName = toState.name
  })
  $scope.$on('$destroy', unregisterStateChange)
  - /**
  - * @summary Get the previous state name
  - * @function
  - * @public
  - *
  - * @returns {String} previous state name
  - *
  - * @example
  - * if (StateController.previousName === 'main') {
  - * console.log('We left the main screen!');
  - * }
  - */
  - this.previousName = null
  -
  /**
  * @summary Get the current state name
  * @function
  