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/d998fe96f60c
Author: AndreiH <andrei.hutusoru@gmail.com>
Desc: Merge pull request #14231 from bobsilverberg/bb

Bug 943844 - [v1.2] Intermittent failures of test_browser_bookmark.py on Travis on v1.2

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https://hg.mozilla.org/integration/gaia-1_2/rev/60812e9664ea
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 943844 - [v1.2] Intermittent failures of test_browser_bookmark.py on Travis on v1.2