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

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https://hg.mozilla.org/integration/gaia-central/rev/d9a8e88b9134
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #19675 from wilsonpage/1015072

Bug 1015072 - Create <gaia-tabs> web-component

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https://hg.mozilla.org/integration/gaia-central/rev/06d8126c8ad5
Author: Wilson Page <wilsonpage@me.com>
Desc: Bug 1015072 - Create <gaia-tabs> web-component
Bumping manifests a=b2g-bump