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

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https://hg.mozilla.org/integration/gaia-central/rev/507ca54e4c4d
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #20745 from AndreiH/1027584

Bug 1027584 - Unxfail persona test

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https://hg.mozilla.org/integration/gaia-central/rev/d35d90b61ea0
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 1027584 - Unxfail persona test
Bumping manifests a=b2g-bump