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

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https://hg.mozilla.org/integration/gaia-central/rev/a8dd09a5d33e
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #14858 from vingtetun/bug951298

Bug 951298 - placing 5 icons in the dock and then going in and out of ed...

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https://hg.mozilla.org/integration/gaia-central/rev/bf9c38e98f08
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 951298 - placing 5 icons in the dock and then going in and out of edit mode on the homescreen will chop the 5th icon. r=crdlc