No, I don't think it's possible without extra JS.
However, I made a version that does use a bit of JS and works fine.
<div><input type="checkbox" ng-click="clickOthers()" ng-model="childCheckbox" /> Child Checkbox</div>
(added to controller)
$scope.clickOthers = function () {
$scope.parentCheckbox = $scope.childCheckbox;
}