Add for-of transform to babel configurations

Summary:
Adds babel-plugin-transform-es2015-for-of to babel configuration.

public

Reviewed By: tadeuzagallo

Differential Revision: D2712220

fb-gh-sync-id: cc6dd9e6e70946607ef9bb9f659eb628cf2eb555

react-packager/.babelrc

@@ -23,7 +23,8 @@
     "transform-object-rest-spread",
     "transform-react-display-name",
     "transform-react-jsx",
-    "transform-regenerator"
+    "transform-regenerator",
+    "transform-es2015-for-of"
   ],
   "sourceMaps": false
 }