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

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https://hg.mozilla.org/integration/gaia-central/rev/5df50375c3c7
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 943183 - [Messages] the bad recipient markers should not be absolutely positioned to a non-scrolled ancestor r=schung

* Add "position: relative" for the absolutely positioned marker's nearest
  ancestor.

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https://hg.mozilla.org/integration/gaia-central/rev/79f39c43ded8
Author: at-kitamura <at-kitamura@kddi-tech.com>
Desc: Bug 917639 - sms application updates time in messages-thread r=julien