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

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https://hg.mozilla.org/integration/gaia-central/rev/f38ad604bb24
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #13915 from vingtetun/bug941024

Bug 941024 - Add a timeout to ensureFullRepaint since screenshoots can t...

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https://hg.mozilla.org/integration/gaia-central/rev/0408c1564876
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 941024 - Add a timeout to ensureFullRepaint since screenshoots can take forever. r=alive