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

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https://hg.mozilla.org/integration/gaia-central/rev/68d44a2c064f
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #21155 from yurenju/xpcshell

Bug 1032051 - Fix jshint error for build/xpcshell-commonjs.js r=@cctuan

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https://hg.mozilla.org/integration/gaia-central/rev/76cc26cf6297
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 1032051 - Fix jshint error for build/xpcshell-commonjs.js
Bumping manifests a=b2g-bump