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

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https://hg.mozilla.org/integration/gaia-central/rev/2f59c42e30dc
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #15138 from RudyLu/homescreen/Bug951563_css_tweak_wvga

Bug 951563 - CSS fix for the 5th row of app label on WVGA resolution.
r=crdlc.

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https://hg.mozilla.org/integration/gaia-central/rev/4fc4645f8697
Author: Rudy Lu <left.lu@gmail.com>
Desc: Bug 951563 - CSS fix for the 5th row of app label on WVGA resolution.