Why is Date.now redefined so that it doesn't return milliseconds from 01-01-1970 as it's the default

```
What steps will reproduce the problem?

1. call Date.now() without including date.js
2. call Date.now() including date.js

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

expected: milliseconds from 01-01-1970
returns: a formated daqte like "Tue Apr 30 2013 15:39:18 GMT+0200 (CEST)"

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

1.0 Alpha-1 Chromium Ubuntu

Please provide any additional information below.

This raises a conflict with an other library wich expects Date.now to return
milliseconds

```

Original issue reported on code.google.com by `imbibin...@gmail.com` on 30 Apr 2013 at 1:42