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

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https://hg.mozilla.org/integration/gaia-central/rev/d28071f9fd22
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #26234 from cctuan/1100789

Bug 1100789 - [NFC] Shrinking should not tilt while utility tray is active

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https://hg.mozilla.org/integration/gaia-central/rev/e8e173f55780
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 1100789 - [NFC] Shrinking should not tilt while utility tray is active
Bumping manifests a=b2g-bump