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

Truncated some number of revisions since the previous bump.

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https://hg.mozilla.org/integration/gaia-central/rev/b406627a0838
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #10412 from alivedise/bugzilla/882053/content-channel-should-trigger-vibration-mode

Bug 882053 - Content channel triggers silent mode incorrectly.r=timdream,a=leo+

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https://hg.mozilla.org/integration/gaia-central/rev/cc24e1635053
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 882053 - Content channel triggers silent mode incorrectly.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "98f8d19dee9d4808e414f5811c0db09afe6adc4a", 
+    "revision": "b406627a0838957e791b588509925cf1e85e1b2f", 
     "repo_path": "/integration/gaia-central"
 }