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

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https://hg.mozilla.org/integration/gaia-central/rev/309ceac79733
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15894 from KevinGrandon/bug_966726_search_rendering

Bug 966726 - Use same renderer for search results r=daleharvey

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https://hg.mozilla.org/integration/gaia-central/rev/8538a5b4798a
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 966726 - Use same renderer for search results r=daleharvey
Bumping manifests a=b2g-bump