Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-1_2/rev/b946d5776d33
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #13593 from wanderview/contacts-group-overflow

Bug 937291:  Limit overflow of each group list.  r=jmcf