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

========

https://hg.mozilla.org/integration/gaia-central/rev/12c35a08fe1b
Author: Rick Waldron <waldron.rick@gmail.com>
Desc: 902973 - [SMS][MMS] Intermittent TEST-UNEXPECTED-FAIL in notification_test.js r=gnarf

https://bugzilla.mozilla.org/show_bug.cgi?id=902973

- Clean up
- Migrate to sinon.spy
- Use mocks as spy targets
- Assert on spy intel instead of mock properties
- Simpify mocks
- Ensure Threads tests start with hash = '';
- Remove from blacklist

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

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "b290b9fde0f137142ec633bdfaf73703c54a8eee", 
+    "revision": "12c35a08fe1b48001dda437be6d378625a4fa44a", 
     "repo_path": "/integration/gaia-central"
 }