Bumping gaia.json for 1 gaia-central revision(s)

========

https://hg.mozilla.org/integration/gaia-central/rev/99bfb0777703
Author: Rick Waldron <waldron.rick@gmail.com>
Desc: Bug 906748 - [Messages] We don't see the cursor when we remove a "number" recipient r=julienw

https://bugzilla.mozilla.org/show_bug.cgi?id=906748

- If nothing "typed" on keyup, assume isDeletingRecipient
- Updates unrelated test in thread_ui

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "b52b2c39126c78f071b6225b913c1e6edcdc06d8", 
+    "revision": "99bfb07777033a2b96f4e7b047dc6cde24b2f02d", 
     "repo_path": "/integration/gaia-central"
 }