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

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https://hg.mozilla.org/integration/gaia-central/rev/64405c99369f
Author: RickyChien <ricky060709@gmail.com>
Desc: Merge pull request #18850 from RickyChien/bug-998776-follow-up

Bug 998776 - Follow-up, update gaia_node_modules.revision r=@RickyChien

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https://hg.mozilla.org/integration/gaia-central/rev/c412ba5a2f4b
Author: Ricky Chien <ricky060709@gmail.com>
Desc: Bug 998776 - Follow-up, update gaia_node_modules.revision

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "3e375bfada88b777879d44ebe75d166fb383de39", 
+    "revision": "64405c99369f239f3df15897c7bdda0078079c9c", 
     "repo_path": "/integration/gaia-central"
 }