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

========

https://hg.mozilla.org/integration/gaia-central/rev/28244f65faf5
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21703 from KevinGrandon/bug_1038178_vertical_scrollroot

Bug 1038178 - [Vertical Homescreen] Use scrollbar from root scrollframe

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https://hg.mozilla.org/integration/gaia-central/rev/db122d234a27
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1038178 - [Vertical Homescreen] Use scrollbar from root scrollframe r=Cwiiis

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "a3213c4e3daf68e93562c5ae8388dbf7a5f933b4", 
+    "revision": "28244f65faf52e48461a1d4d2a8ac40a5343cb8e", 
     "repo_path": "/integration/gaia-central"
 }