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

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https://hg.mozilla.org/integration/gaia-1_4/rev/19cbfd502f6d
Author: Andrew Sutherland <asutherland@asutherland.org>
Desc: Merge pull request #19010 from asutherland/v1.4-virt-list-slice-fix

Bug 1004137 - [email] Absolute positioned virtual list regression: Refresh-synced folder not showing newly added message outside date range. r=jrburke. a=1.4+

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https://hg.mozilla.org/integration/gaia-1_4/rev/893d877f7828
Author: Andrew Sutherland <asutherland@asutherland.org>
Desc: Merge pull request #19007 from asutherland/email-virt-list-slice-fix

Bug 1004137 - [email] Absolute positioned virtual list regression: Refresh-synced folder not showing newly added message outside date range. r=jrburke. a=1.4+
Bumping manifests a=b2g-bump