Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/629003f982d7
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #11571 from gasolin/issue-903049

Bug 903049 - [Browser] Top Sites are Blurry r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/3cd030925e41
Author: gasolin <gasolin@gmail.com>
Desc: Bug 903049 - [Browser] Top Sites are Blurry