Add a year (365 or 366 days) to de current day

```
What steps will reproduce the problem?
var start = Date.today();
var end = Date.parse(start, "d-MMM-yyyy");
end.addYears(1); //one year later
console.log(end);

What is the expected output? What do you see instead?
the difference between 'start' and 'end' should be 365 or 366 days, depending
of the year, leap year or not.

What version of the product are you using? On what operating system?
version: Nov 2007

Please provide any additional information below.

Should I add days manually? Why is not working addYears(1) ??

Thanks in advance

```

Original issue reported on code.google.com by `jose.ros...@gmail.com` on 27 Feb 2012 at 12:13