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

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https://hg.mozilla.org/integration/gaia-central/rev/389523ab2cb8
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Merge pull request #19613 from eeejay/bug-1015479

Bug 1015479 - Make header markup follow visual order. r=arnau

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https://hg.mozilla.org/integration/gaia-central/rev/0ed2c333bd4c
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 1015479 - Make header markup follow visual order.

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https://hg.mozilla.org/integration/gaia-central/rev/9282b03d2d2c
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #20364 from crdlc/bug-1023011

Bug 1023011 - (vertical-homescreen) Implement pressed state visual for App Icons

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https://hg.mozilla.org/integration/gaia-central/rev/6a00afcf8dba
Author: crdlc <crdlc@tid.es>
Desc: Bug 1023011 - (vertical-homescreen) Implement pressed state visual for App Icons
Bumping manifests a=b2g-bump