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/16b5a392e63c
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15086 from davidflanagan/bug939679v1.2

Merge pull request #14912 from davidflanagan/bug939679

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https://hg.mozilla.org/integration/gaia-1_2/rev/ed87a17f00a8
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #14912 from davidflanagan/bug939679

Bug 939679: compute the right camera preview size on HD devices r=dmarcos(cherry picked from commit 4245fb93e747d3e3cc9e50ba6fa2f084c9cb682f)

Conflicts:

	apps/camera/js/camera.js