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

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https://hg.mozilla.org/integration/gaia-2_0/rev/411a3e883a0b
Author: Ghislain 'Aus' Lacroix <aus@noiseport.org>
Desc: Merge pull request #20956 from nullaus/v2.0

Merge pull request #20939 from nullaus/bug1027414

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https://hg.mozilla.org/integration/gaia-2_0/rev/8c1c0251a5ef
Author: Ghislain 'Aus' Lacroix <aus@noiseport.org>
Desc: Merge pull request #20939 from nullaus/bug1027414

bug 1027414 - Dismiss on visibilitychange r=alive (on behalf of 21)
(cherry picked from commit 217b6fac31a8eaa1f74dfff95239fbc29eae4dd4)
Bumping manifests a=b2g-bump