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

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https://hg.mozilla.org/integration/gaia-1_4/rev/b6b9e1f3004f
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #19572 from justindarc/bug1008349-v1.4

Bug1008349 v1.4

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https://hg.mozilla.org/integration/gaia-1_4/rev/86cc391e3365
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Bug 1008349 - [B2G][Camera][Zoom][Open C]zoom level in preview is higher than the zoom level of the picture taken.
Bumping manifests a=b2g-bump