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

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https://hg.mozilla.org/integration/gaia-central/rev/5477def773c7
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21563 from KevinGrandon/bug_1029766_collection_intermittent_test

Bug 1029766 - Intermittent TEST-UNEXPECTED-FAIL | collection_test.js | Vertical - Collection drag icon (/w entry point) into collection

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https://hg.mozilla.org/integration/gaia-central/rev/4bb0e8e3368e
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1029766 - Intermittent TEST-UNEXPECTED-FAIL | collection_test.js | Vertical - Collection drag icon (/w entry point) into collection r=crdlc
Bumping manifests a=b2g-bump