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

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https://hg.mozilla.org/integration/gaia-central/rev/ad3180726740
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #18894 from etiennesegonzac/bug-996692-fullscreen-statusbar-regression

Bug 996692 - Fixing the fullscreen statusbar regression r=benfrancis r=kevingrandon

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https://hg.mozilla.org/integration/gaia-central/rev/87c98ebe664d
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 996692 - Fixing the fullscreen statusbar regression and update the test to catch it next time.
r=kgrandon
Bumping manifests a=b2g-bump