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

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https://hg.mozilla.org/integration/gaia-central/rev/d37aa6da234a
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #18045 from pivanov/bug-992994

Bug 992994 - [VDR][Email] Apply Buttons and Input areas [BB]

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https://hg.mozilla.org/integration/gaia-central/rev/b8526a8fc5c4
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 992994 - [VDR][Email] Apply Buttons and Input areas [BB]

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https://hg.mozilla.org/integration/gaia-central/rev/2ea6fe089d2f
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #19178 from KevinGrandon/bug_1009269_home2_bookmarks_test

Bug 1009269 - Intermittent failing test, Vertical - Bookmark Bookmarking appends to last group

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https://hg.mozilla.org/integration/gaia-central/rev/f4b197755220
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1009269 - Intermittent failing test, Vertical - Bookmark Bookmarking appends to last group
Bumping manifests a=b2g-bump