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

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https://hg.mozilla.org/integration/gaia-central/rev/3e26562fdae3
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #24951 from KevinGrandon/bug_1079699_system_homescreen_hash

Bug 1079699 - [System] Do not grow the home screen iframe src forever

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https://hg.mozilla.org/integration/gaia-central/rev/728085e97e55
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1079699 - [System] Do not grow the home screen iframe src forever r=sfoster
Bumping manifests a=b2g-bump