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

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https://hg.mozilla.org/integration/gaia-central/rev/f70bacc2777c
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Merge pull request #12504 from comoyo/keyboard_pop_down

Bug 912033 - Pop down animation keyboard. r=GaryChen

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https://hg.mozilla.org/integration/gaia-central/rev/3875247397c1
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Bug 912033 - Pop down animation keyboard