Doesn't work with custom array prototype extensions.

If 'Array' type is extended like below, enumeration using `for (var i in ...)` doesn't work as expected.

```
Array.prototype.foo = function() { console.log("hi"); }
a = [1,2,3,4,5];
for (var i in a) {
  console.log(i); //foo will be enumerated
}
```

This causes invalid regular expression error in `validate_phone_iso3166` function.
