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

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https://hg.mozilla.org/integration/gaia-central/rev/84c55a230c57
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #16348 from julienw/973490-npm-link

Bug 973490 - [TestAgent] don't run `npm install` if `npm ink` is used r=...

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https://hg.mozilla.org/integration/gaia-central/rev/fd6b8c15e5ac
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 973490 - [TestAgent] don't run `npm install` if `npm ink` is used r=yurenju
Bumping manifests a=b2g-bump