Bumping gaia.json for 1 gaia-central revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/77ae19d9facf
Author: Mike Pennisi <mike@mikepennisi.com>
Desc: Revert "Bug 937630 - Remove scaling transition of lock screen to make it 60fps"

This reverts commit 9b3f7e22f7b548f10f07ba55293a682a5a2ed7bf.

The Lockscreen components partially cover the application surface.