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

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https://hg.mozilla.org/integration/gaia-central/rev/ac0ba06a1aee
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #14392 from huchengtw-moz/gallery/Bug_946327_two_activity_handling

Bug 946327 - [B2G][SMS][MMS] Tapping multiple times rapidly on a sent or..., r=djf

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https://hg.mozilla.org/integration/gaia-central/rev/a65b973cf264
Author: John Hu <johu@mozilla.com>
Desc: Bug 946327 - [B2G][SMS][MMS] Tapping multiple times rapidly on a sent or received photo in Messages app results in invalid/corrupt erro