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

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https://hg.mozilla.org/integration/gaia-central/rev/9ac4336f49fb
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #15732 from crdlc/bug-938287

Bug 964337 - Implementation a mechanism to edit Homescreen Bookmarks

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https://hg.mozilla.org/integration/gaia-central/rev/5181d7e2b3b9
Author: crdlc <crdlc@tid.es>
Desc: Bug 964337 - Implementation a mechanism to edit Homescreen Bookmarks
Bumping manifests a=b2g-bump