Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5c602d0a382e
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #20159 from eeejay/bug-1020605

Bug 1020605 - (gaia-grid) Append all children to shadow root by removing selector tag.

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https://hg.mozilla.org/integration/gaia-central/rev/19bc301d242b
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 1020605 - (gaia-grid) Append all children to shadow root by removing <content> selector tag.

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https://hg.mozilla.org/integration/gaia-central/rev/fdd383848df7
Author: Sherman Chen <shamenchens@users.noreply.github.com>
Desc: Merge pull request #20113 from shamenchens/Bug1021327-Flatfish-verticalhome-nodefault

Bug 1021327 Flatfish verticalhome not default, r=yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/3c38f14ffdbd
Author: Sherman Chen <shamen.chens@gmail.com>
Desc: Bug 1021327 Flatfish verticalhome not default
Bumping manifests a=b2g-bump