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

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https://hg.mozilla.org/integration/gaia-central/rev/2ad1a26f5fd1
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #19180 from eeejay/bug-1009295

Bug 1009295 - Give homescreen tiles a role of "link" r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/c73d34af42dd
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 1009295 - Give homescreen tiles a role of "link".
Bumping manifests a=b2g-bump