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

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https://hg.mozilla.org/integration/gaia-central/rev/138a50b76561
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #17642 from crdlc/bug-988172

Bug 988172 - Create datastore for bookmarks and extract the UI to add th...

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https://hg.mozilla.org/integration/gaia-central/rev/8985d0c3b07a
Author: crdlc <crdlc@tid.es>
Desc: Bug 988172 - Create datastore for bookmarks and extract the UI to add them to system

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "8102aa922fc5270b490803e15c8e13022e194da8", 
+    "revision": "138a50b765612b5469efbd27f64f6b06ceb0ee2b", 
     "repo_path": "/integration/gaia-central"
 }