facebook/regenerator — pull request #95 by benjamn (2014-03-08 23:52:03+00:00)
Title: Reduce for-in boilerplate by making Context#keys return an iterator

With these changes, a for-in loop like this:
```js
before();
for (var key in obj) {
inside();
}
after();
```
now generates code like this:
```js
before();
$ctx17.t13 = $ctx17.keys(obj);
case 3:
if (($ctx17.t14 = $ctx17.t13.next()).done) {
$ctx17.next = 11;
break;
}
key = $ctx17.t14.value;
inside();
$ctx17.next = 3;
break;
case 11:
after();
```
cc @amasad @qfox