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

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https://hg.mozilla.org/integration/gaia-central/rev/4b8c8dc5811d
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #12636 from crdlc/bug-923401

Bug 923401 - The collection title should be showed when it is opened always without exception

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https://hg.mozilla.org/integration/gaia-central/rev/f260d91cf246
Author: crdlc <crdlc@tid.es>
Desc: Bug 923401 - The collection title should be showed when it is opened always without exception