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

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https://hg.mozilla.org/integration/gaia-central/rev/af1c2fdc3e4b
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #18484 from dominickuo/bug-910055

Bug 910055 - [Settings] add media slider to the sound region, r=crh0716

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https://hg.mozilla.org/integration/gaia-central/rev/a33bf018f9ff
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 910055 - [Settings] add media slider to the sound region

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "dd94fb2c581d0013a3d679c469804f71bc8489d2", 
+    "revision": "af1c2fdc3e4b0ce424ba65f4eed79b5fdd373892", 
     "repo_path": "/integration/gaia-central"
 }