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

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https://hg.mozilla.org/integration/gaia-central/rev/a6e35072f019
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #20552 from cctuan/1024933

Bug 1024933 - [Text Selection] Utility bubble's shadow improvement

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https://hg.mozilla.org/integration/gaia-central/rev/58ac9bbac4e2
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 1024933 - [Text Selection] Utility bubble's shadow improvement
Bumping manifests a=b2g-bump