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

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https://hg.mozilla.org/integration/gaia-central/rev/e86b294efd18
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #16598 from alivedise/bugzilla/962352/do-not-restore-caller-on-home-button

Bug 962352 - restore the caller only when activity callee is active, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/c708caf8f21b
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 962352 - restore the caller only when activity callee is active
Bumping manifests a=b2g-bump