Translating ActionScript Date from UTC to local time with milliseconds from epoch
===

This is a follow up on my [previous question][1]. In my solution to get current time, I need to add/subtract offset:

    var createDate:Date = new Date();
    var offset:Number = createDate.getTimezoneOffset() * 60 * 1000; 
    createDate.time = parseInt("1343174921") * 1000 - offset; // subtracting offset

To get correct time, I had to subtract offset(pure guess).  How do I know to subtract or add offset? The documentation for [getTimezoneOffset][2] says: 

> this value is the number of minutes you need to add to
> the computer's local time to equal UTC. If your computer's time is set
> later than UTC, the value will be negative.

Is there an easy way to figure out if computer's time is set later/earlier than UTC so that I know if I need to add or subtract offset?


  [1]: http://stackoverflow.com/questions/11632421/creating-actionscript-date-object-from-mysql-utc-timestamp-string
  [2]: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/Date.html#timezoneOffset