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

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https://hg.mozilla.org/integration/gaia-central/rev/cea79abbb7a9
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #15966 from timdream/keyboard-build-2

Revert "Revert "Merge pull request #15857 from comoyo/bug964216""

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https://hg.mozilla.org/integration/gaia-central/rev/9778b9f6a597
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Revert "Revert "Merge pull request #15857 from comoyo/bug964216""

This reverts commit 33eb812eadb61f76744103105e099972a8255843.
Bumping manifests a=b2g-bump