Description:
------------
We were using part of the code below to work out time zone differences, however when HST10HDT was entered it was giving an exception, even although it's a valid timezone.

Reproduce code:
---------------
<?
  try {
    #DateTimeZone Object for TimeZone for this phone
    $tz = 'HST10HDT';
    $cdto = new DateTimeZone($tz);
} catch(Exception $e) {
   print "Exception!\n";
   print " ---> ".$e->getMessage()."\n";
   exit;
}

print "No Exception!\n";

?>


Expected result:
----------------
No Exception!

Actual result:
--------------
Exception!
 ---> DateTimeZone::__construct(): Unknown or bad timezone (HST10HDT)