Date.parseExact returns (in)valid date when month is 0

```
What steps will reproduce the problem?
1. FireBug Command Line:
>>> Date.parseExact("01.00.2010","dd.MM.yyyy");

What is the expected output? What do you see instead?
Expected: null
Instead: Tue Dec 01 2009 00:00:00 GMT+0100 (Central Europe Standard Time) {
_orient=1, more...}

What version of the product are you using? On what operating system?
date-sl-SI.js
* @version: 1.0 Alpha-1
* @date: 2008-05-13
Windows XP Pro SP3, firefox, chrome, IE, opera

Please provide any additional information below.

parseExact should return null if a string cannot be converted to a valid date
and as such acts as a first line of defense againt incorrect data entry.
```

Original issue reported on code.google.com by `ales.vau...@gmail.com` on 15 Aug 2010 at 9:05