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

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https://hg.mozilla.org/integration/gaia-central/rev/26a239d80401
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #19296 from etiennesegonzac/bug-1011072

Bug 1011072 - Pre-position appwindow for edge gestures in an orientation independent way. r=21

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https://hg.mozilla.org/integration/gaia-central/rev/953580d1f48b
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 1011072 - Pre-position appwindow for edge gestures in an orientation independent way.
Bumping manifests a=b2g-bump