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

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https://hg.mozilla.org/integration/gaia-central/rev/fb0904055ca5
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #22674 from yzen/bug-1030425

Bug 1030425 - screen manager now listens to accessibility action events ...

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https://hg.mozilla.org/integration/gaia-central/rev/280bc209c557
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1030425 - screen manager now listens to accessibility action events that reset the idle timeout. r=alive
Bumping manifests a=b2g-bump