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

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https://hg.mozilla.org/integration/gaia-central/rev/89b1153afdf6
Author: Hubert Figuière <hub@figuiere.net>
Desc: Merge pull request #23750 from hfiguiere/bug1063347

Bug 1063347 - change path.existsSync with fs.existsSync. r=yuren

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https://hg.mozilla.org/integration/gaia-central/rev/bb8f3903c8e4
Author: Hubert Figuière <hub@figuiere.net>
Desc: Bug 1063347 - change path.existsSync with fs.existsSync.
Bumping manifests a=b2g-bump