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

========

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

========

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

========

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.

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "50dfd8b9dafb023667603fed0475b786298712e1", 
+    "revision": "4763231f664a8a94cbea98b35b84749b51a961c9", 
     "repo_path": "/integration/gaia-central"
 }