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

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https://hg.mozilla.org/integration/gaia-central/rev/0c4b87f3bee9
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #12469 from crdlc/bug-920948

Bug 920948 - [Bug] Sometimes drag&drop is not working fine with collections

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https://hg.mozilla.org/integration/gaia-central/rev/1f54f42eea24
Author: crdlc <crdlc@tid.es>
Desc: Bug 920948 - [Bug] Sometimes drag&drop is not working fine with collections