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

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https://hg.mozilla.org/integration/gaia-central/rev/88b6b2fdab9e
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #22589 from vingtetun/app_chrome-cleanup

Bug 1049831 - Remove app_chrome.js dead code. r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/1091eea683fe
Author: Vivien Nicolas <vnicolas@mozilla.com>
Desc: Bug 1049831 - Remove app_chrome.js dead code. r=kgrandon
Bumping manifests a=b2g-bump