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

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https://hg.mozilla.org/integration/gaia-1_3/rev/516de52e2c78
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #16914 from julienw/979983-v1.3-fix-gjslint-issues

Bug 979983 - Fix gjslint issues on v1.3

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https://hg.mozilla.org/integration/gaia-1_3/rev/b6721d0284a2
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 979983 - Fix gjslint issues on v1.3
Bumping manifests a=b2g-bump