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

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https://hg.mozilla.org/integration/gaia-central/rev/ab0d6e1927a4
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #13399 from crdlc/bug-935077

Bug 935070 - [Download Manager] New shared component DownloadUI

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https://hg.mozilla.org/integration/gaia-central/rev/8f978d90a82f
Author: crdlc <crdlc@tid.es>
Desc: Bug 935070 - [Download Manager] New shared component DownloadUI