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

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https://hg.mozilla.org/integration/gaia-central/rev/cf4cef589d40
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #16328 from vingtetun/bug963499.jank

Bug 963499 - Add a JS jank watcher to the Developer HUD. r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/d92c9166b5cf
Author: Jan Keromnes <janx@linux.com>
Desc: Bug 963499 - Add a JS jank watcher to the Developer HUD. r=vingtetun
Bumping manifests a=b2g-bump