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

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https://hg.mozilla.org/integration/gaia-central/rev/4b7a20107e22
Author: Rex KM Lee <rexboy@mozilla.com>
Desc: Merge pull request #10670 from rexboy7/fixhd-887742

Fix bug 887742 - Let GAIA_DEV_PIXELS_PER_PX valid for files in resources/branding

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https://hg.mozilla.org/integration/gaia-central/rev/010e52ab13ba
Author: Rex Lee <rexboy@mozilla.com>
Desc: Fix bug 887742 - Let GAIA_DEV_PIXELS_PER_PX valid for files in resources/branding