Bumping gaia.json for 2 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/89380bda73c2
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #13842 from AndreiH/calendar-app-object_v1.2

Bug 937532 - Migrate calendar tests to use an app object

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https://hg.mozilla.org/integration/gaia-1_2/rev/a6453114ecf3
Author: Johan LORENZO <johan.lorenzo@gmail.com>
Desc: Bug 937532 - Migrate calendar tests to use an app object