use $rootScope instead of $scope.$root

Author: zacronos

src/ui-scroll.js

@@ -349,7 +349,7 @@ angular.module('ui.scroll', [])
           let updates = updateDOM();
 
           // We need the item bindings to be processed before we can do adjustment
-          !$scope.$$phase && !$scope.$root.$$phase && $scope.$digest();
+          !$scope.$$phase && !$rootScope.$$phase && $scope.$digest();
 
           updates.inserted.forEach(w => w.element.removeClass('ng-hide'));
           updates.prepended.forEach(w => w.element.removeClass('ng-hide'));
@@ -370,7 +370,7 @@ angular.module('ui.scroll', [])
           let updates = updateDOM();
 
           // We need the item bindings to be processed before we can do adjustment
-          !$scope.$$phase && !$scope.$root.$$phase && $scope.$digest();
+          !$scope.$$phase && !$rootScope.$$phase && $scope.$digest();
 
           updates.inserted.forEach(w => w.element.removeClass('ng-hide'));
           updates.prepended.forEach(w => w.element.removeClass('ng-hide'));