startTime and endTime wrong if GA was not started on creation

[maherm]

See https://www.steamgifts.com/discussion/kceto/userscript-sg-bookmarks-save-giveaways-for-later-use#0I9XrGt

If that's the case, you can only get EITHER startDate OR endDate, but never both - depending on whether the GA already has started or not.
Also affected by this bug are the calculations of hasStarted, hasEnded and isRunning.