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

========

https://hg.mozilla.org/integration/gaia-central/rev/50e6f76436eb
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #21654 from timdream/keyboard-alt-sublayout

Bug 1037942 - Normalize alt in overwrite alternative layouts, r=rudyl

========

https://hg.mozilla.org/integration/gaia-central/rev/f54018b582b3
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 1037942 - Normalize alt in overwrite alternative layouts

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "2b52e85304b92d1e6017668d12e5e8e1d2b48aae", 
+    "revision": "50e6f76436ebd17258236a47241ab4ea4422e764", 
     "repo_path": "/integration/gaia-central"
 }