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

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https://hg.mozilla.org/integration/gaia-central/rev/9a04d1f511e0
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #13159 from huchengtw-moz/build/Bug_921417_rewrite_variant.py_to_js

Bug 921417 - rewrite build/variant.py in javascript, r=yurenju, acperez

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https://hg.mozilla.org/integration/gaia-central/rev/9c95a7c9a985
Author: John Hu <johu@mozilla.com>
Desc: Bug 921417 - rewrite build/variant.py in javascript