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

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https://hg.mozilla.org/integration/gaia-central/rev/4a77df0c9d0a
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Merge pull request #15044 from comoyo/new_keyboard_promisify

Bug 975992 - Keep keyboard2 state in Gecko rather than Gaia. r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/a14838613ff3
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Bug 975992 - Keep keyboard2 state in Gecko rather than Gaia
Bumping manifests a=b2g-bump