Loops not broken in nested loop

Hi,

Thanks for the useful library! I have come across a case where infinite loops are not broken:

```js
for (var i = 0; i < 10; i = i + 1) {
    for (var j = 0; j < 10; i = i + 1) {
    }
}
```

I haven’t had a chance to investigate yet, and will do so when time allows. But wanted to let you know as soon as I came across it.