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

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https://hg.mozilla.org/integration/gaia-central/rev/d2996703d137
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #19399 from EricRahm/bug_992226

Bug 992226 - Awesomescreen leaks blob URLs for favicons r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/9eb245353d3b
Author: Eric Rahm <erahm@mozilla.com>
Desc: Bug 992226 - Awesomescreen leaks blob URLs for favicons
Bumping manifests a=b2g-bump