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

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https://hg.mozilla.org/integration/gaia-central/rev/3e3eb020773e
Author: Zibi Braniecki <zbigniew.braniecki@gmail.com>
Desc: Merge pull request #25087 from zbraniecki/941969-optimize-js-for-system-app

Bug 941969 - Optimize JS for system app. r=ochameau

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https://hg.mozilla.org/integration/gaia-central/rev/7f62aef20e94
Author: Zbigniew Braniecki <gandalf@mozilla.com>
Desc: Bug 941969 - Optimize JS for system app
Bumping manifests a=b2g-bump