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

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https://hg.mozilla.org/integration/gaia-central/rev/4b602663e947
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #14566 from alivedise/bugzilla/943717/app-window-factory-creation

Bug 943717 - Refine Instantication of AppWindow and ActivityWindow, r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/dca37d4995f5
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 943717 - Refine Instantication of AppWindow and ActivityWindow