fix year char count test

A fix for https://github.com/google/closure-library/issues/384

```
var date = new Date();
var p = new goog.i18n.DateTimeParse("MM'/'dd'/'yyyy"); // notice that we expect a 4-digit year
var res = p.strictParse("01/01/01", date); //  expected 0, but got 8
```