Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/4763231f664a
Author: Yi-Fan Liao <yliao@mozilla.com>
Desc: Merge pull request #25319 from begeeben/1074622_scaffold_the_tv_browser

Bug 1074622 - [Stingray] Scaffold the TV browser, r=:timdream, :rexboy, :evelyn

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https://hg.mozilla.org/integration/gaia-central/rev/63fa2dc0d777
Author: Yi-Fan Liao <begeeben@gmail.com>
Desc: Bug 1074622 - [Stingray] Scaffold the TV browser

* Restructure HTML structure and style for TV browser UI.
* Draft modules for TV browser.
* add tv_apps/browser in build/config/tv/apps-engineering.list

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https://hg.mozilla.org/integration/gaia-central/rev/93991bb8ff31
Author: Yi-Fan Liao <begeeben@gmail.com>
Desc: Bug 1074622 - [Stingray] Scaffold the TV browser

* Clone apps/browser to tv_apps/browser.
Bumping manifests a=b2g-bump