Contribution Page credit card expiry months are incorrectly offset when the timezone is Whitehorse
Found an interesting bug that only happens with users who have chose the America/Whitehorse timezone (-0700). It does not happen if we chose another similar timezone (America/Vancouver, America/Yellowknife, etc).
To reproduce on dmaster / drupal7:
- login as the demo user
- change the user's timezone to America/Whitehorse
Then go to a contribution page:
https://dmaster.demo.civicrm.org/civicrm/contribute/transact?reset=1&id=2