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

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https://hg.mozilla.org/integration/gaia-central/rev/2592df7f30e7
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #20163 from mikehenrty/bug-1021133-fontstyle

Bug 1021133 - make getFontWidth fontStyle aware

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https://hg.mozilla.org/integration/gaia-central/rev/07ff40d441cf
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1021133 - make getFontWidth fontStyle aware
Bumping manifests a=b2g-bump