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

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https://hg.mozilla.org/integration/gaia-central/rev/77ac5306cad9
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #12919 from wanderview/contacts-duplicate-tests

Bug 927877: Check if img is already loaded.  r=arcturus

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https://hg.mozilla.org/integration/gaia-central/rev/12135a94b83f
Author: Ben Kelly <ben@wanderview.com>
Desc: Bug 927877: Check if img is already loaded.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "e4da7eb21f88849010d72125576c178bdfd7f722", 
+    "revision": "77ac5306cad9307e7b9ac6ca382bca44b55df368", 
     "repo_path": "/integration/gaia-central"
 }