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

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https://hg.mozilla.org/integration/gaia-central/rev/8ed9c87f727a
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #20268 from alivedise/bugzilla/1022943/swipe-navigation-icon

Bug 1022943 - Update swipe navigation icon, r=arthur

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https://hg.mozilla.org/integration/gaia-central/rev/4265c3184b31
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 1022943 - Update swipe navigation icon
Bumping manifests a=b2g-bump