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/3f55783a74ee
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #14505 from AlinT/12bug_937336

Bug 937336 - Remove explicit frame switching from Homescreen/everything ...

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https://hg.mozilla.org/integration/gaia-1_2/rev/002de3b0eb78
Author: AlinT <trifandreialin@gmail.com>
Desc: Bug 937336 - Remove explicit frame switching from Homescreen/everything me app objects and tests