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

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https://hg.mozilla.org/integration/gaia-central/rev/8b613bca5524
Author: Ian Liu <iliu@mozilla.com>
Desc: Merge pull request #13414 from ian-liu/system/Bug907825_Floating_pixels_above_checkmarks_on_value_selector_screen

Bug 907825 - [System] [HD] Floating pixels above checkmarks on value selector screen, r=@RudyLu

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https://hg.mozilla.org/integration/gaia-central/rev/24c3d1b939a2
Author: ian-liu <iliu@mozilla.com>
Desc: Bug 907825 - [System] [HD] Floating pixels above checkmarks on value selector screen