Bumping gaia.json for 1 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/eccf3254971b
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Revert "Bug 909839 - Merge JavaScript 'atoms' used by gaia and gaiatest. r=jgriffin r=hfiguiere r=zcampbell"

This reverts commit 2c09f900a6bd9c07891f58027ffab54ad3c176e9.