Даже ещё проще (не работает)
<!DOCTYPE HTML>
<html lang="en" ng-app>
<head>
    <title>Test</title>
    <script type="text/javascript" src="js/angular/angular.min.js"></script>
    <script type="text/javascript">
        function FeaturesListCtrl($scope) {
            $scope.firstLevel = [
                { a: '1' }, 
                { a: '2' }, 
                { a: '3' }
            ];
            $scope.GetSecondLevel = function () {
                return [
                    { b: '11' },
                    { b: '22' }
                ];
            }
        }
    </script>
</head>
<body>
    <input type="button" onclick="GenerateEvent()" value="Event">
    <div ng-controller='FeaturesListCtrl'>
        <ul>
            <li ng-repeat='level1 in firstLevel'>
                {{level1.a}}
                <ul>
                    <li ng-repeat='level2 in GetSecondLevel()'>
                        {{level2.b}}
                    </li>
                </ul>
            </li>
        </ul>
    </div>
</body>
</html>