Bumping gaia.json for 3 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/9aa3da2da145
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 883616 - Bug 882607 resolution introduced a XSS vulnerability r=gnarf

Carefully escape the body before injecting it into the document
Added some tests to ensure this for both SMS and MMS.

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https://hg.mozilla.org/integration/gaia-central/rev/7963fee0efae
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #10525 from alivedise/bugzilla/885473_master_v2/software-button-pressed

Bug 885471 - 1. Fix software button manager on real device and nightly and simulator; 2. Add holdhome event. r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/3611bb710864
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 885471 - Fix software button manager default behavior on real
device/nightly/simulator, and add holdhome event.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "7615f637d227eba928077fa4117143af990edf7c", 
+    "revision": "9aa3da2da145479b1688abd4ff9a75b731f17f0d", 
     "repo_path": "/integration/gaia-central"
 }