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

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https://hg.mozilla.org/integration/gaia-central/rev/5f97dc27db8f
Author: Jan Keromnes <janx@linux.com>
Desc: Merge pull request #20146 from jankeromnes/uss

Bug 976024 - Unique Set Size in the Developer HUD. r=21

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https://hg.mozilla.org/integration/gaia-central/rev/16a14716b466
Author: Jan Keromnes <janx@linux.com>
Desc: Bug 976024 - Unique Set Size in the Developer HUD. r=21
Bumping manifests a=b2g-bump