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

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https://hg.mozilla.org/integration/gaia-central/rev/a4d472efb940
Author: punamdahiya <punamdahiya@yahoo.com>
Desc: Merge pull request #12717 from punamdahiya/Bug924170_Video_Marionette_Tests

Bug924170 - [Video] - Add Marionette tests for Video App r=jugglinmike

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https://hg.mozilla.org/integration/gaia-central/rev/ecc458fabefe
Author: Punam Dahiya <punamdahiya@yahoo.com>
Desc: Bug924170 - [Video] - Add Marionette tests for Video App r=jugglinmike

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "b41fabfb74c10dd3368e7a93c1f2f46299a926bb", 
+    "revision": "a4d472efb940071db42ab2554fcb4e9119f41dd0", 
     "repo_path": "/integration/gaia-central"
 }