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

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https://hg.mozilla.org/integration/gaia-central/rev/e8323d97975a
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #12891 from viorelaioia/bug-926357

Bug 926357 - Write a test to use the 'Number' keyboard

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https://hg.mozilla.org/integration/gaia-central/rev/f93b1720e937
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 926357 - Write a test to use the 'Number' keyboard