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

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https://hg.mozilla.org/integration/gaia-central/rev/10bb252685ef
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #12610 from snowmantw/issue921392

Bug 921392 - [LockScreen] Need to dark the icons of locksceen

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https://hg.mozilla.org/integration/gaia-central/rev/93aa21239ed4
Author: Greg Weng <snowmantw@gmail.com>
Desc: Bug 921392 - [LockScreen] Need to dark the icons of locksceen