(function (a) {
  var ownProps = [];
  for (var s in a) {
    if (a.hasOwnProperty(s)) {
      ownProps.push(s);
    }
  }
  return ownProps;
})((function () {
  var a = [];
  Object.defineProperty(a, 'foo', {value: 'Foo'});
  Array.prototype.push.call(a, 'a', 'b');
  return a;
})())