If I update my Safari 7.0.6 to Safari 8, will I lose or damage my Contacts?
If I update my Safari 7.0.6 to Safari 8, will I lose or damage my Contact list?
MacBook Air (13-inch Late 2010), OS X Mavericks (10.9.5)
The only way to upgrade from Safari 7 to Safari 8 is to upgrade the whole operating system to Yosemite. Nothing should happen to your contacts, but there's always a slight chance that something will go wrong. That's why you have backups.