doesn't handle +0000

```
What steps will reproduce the problem?
1. Date.parse("2010-09-18 12:00:00 +0000")

What is the expected output? What do you see instead?

Expect a Date like: "2010-09-18 08:00:00 GMT-0400"

Instead, I get the original time (12:00) AND a specified timezone offset (in my
case GMT-0400), like "2010-09-18 12:00:00 GMT-0400".

What version of the product are you using? On what operating system?

Please provide any additional information below.

Probably the comparison "if (this.timezoneOffset)" is what does it.

```

Original issue reported on code.google.com by `petera...@gmail.com` on 14 Sep 2010 at 5:58