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

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https://hg.mozilla.org/integration/gaia-central/rev/064b829074c2
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #12591 from arcturus/contacts-select-perf-1

Bug 902873 - [Contacts] Performance improvements when selecting in contact list

========

https://hg.mozilla.org/integration/gaia-central/rev/e752f78551bc
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Bug 902873 - [Contacts] Performance improvements when selecting in contact list

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "bf9c093d17fd0462f92092ba6d18f584a3210a18", 
+    "revision": "064b829074c2088d866b022c8d942c07744ff9b9", 
     "repo_path": "/integration/gaia-central"
 }