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

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https://hg.mozilla.org/integration/gaia-central/rev/53c3656a9e95
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #18448 from gasolin/issue-968695

Bug 968695 - [settings] add marionette test for Application storage pane..., r=arthur

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https://hg.mozilla.org/integration/gaia-central/rev/15d58dfb8ee1
Author: gasolin <gasolin@gmail.com>
Desc: Bug 968695 - [settings] add marionette test for Application storage panel

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "4df063ef639a668d2eea38f2b64831a52344e0b3", 
+    "revision": "53c3656a9e95834e2259b3d267a256b031308684", 
     "repo_path": "/integration/gaia-central"
 }