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

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https://hg.mozilla.org/integration/gaia-central/rev/d63658864198
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #15868 from benfrancis/963880

Bug 963880 - Fix broken bookmark entry sheet when switching orientation r=daleharvey

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https://hg.mozilla.org/integration/gaia-central/rev/e2f578f731c8
Author: Ben Francis <ben@tola.me.uk>
Desc: Bug 963880 - Fix broken bookmark entry sheet when switching orientation
Bumping manifests a=b2g-bump