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

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https://hg.mozilla.org/integration/gaia-central/rev/8e0bdad94977
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #19219 from etiennesegonzac/bug-1009950-edge-gestures-on

Bug 1009950 - Turning the app-to-app edge gesture on by default. r=gwagner,21

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https://hg.mozilla.org/integration/gaia-central/rev/d6f5bca247f6
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 1009950 - Turning the app-to-app edge gesture on by default.
Bumping manifests a=b2g-bump