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

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https://hg.mozilla.org/integration/gaia-central/rev/469f4a743f4b
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #18388 from zbraniecki/994417-primaryinfo-tostring

Bug 994417 - Stringify an object before passing as placeable

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https://hg.mozilla.org/integration/gaia-central/rev/a88e264f44c0
Author: Zbigniew Braniecki <gandalf@mozilla.com>
Desc: Bug 994417 - Stringify an object before passing as placeable
Bumping manifests a=b2g-bump