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

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https://hg.mozilla.org/integration/gaia-central/rev/2ac3dd299034
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15892 from davidflanagan/bug959049v2

Merge pull request #15702 from davidflanagan/bug959049

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https://hg.mozilla.org/integration/gaia-central/rev/6c993c3a6733
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #15702 from davidflanagan/bug959049

Bug 959049: reduce keyboard row height and font-size in landscape mode(cherry picked from commit cfeb5bf7e7665e4be412d1f774bd46fadeff3c93)

fix lint
Bumping manifests a=b2g-bump