Merge pull request #654 from mozilla/greenkeeper-babel-preset-stage-2-6.11.0

Update babel-preset-stage-2 to version 6.11.0 🚀

package.json

@@ -162,7 +162,7 @@
     "babel-polyfill": "6.9.1",
     "babel-preset-es2015": "6.9.0",
     "babel-preset-react": "6.11.0",
-    "babel-preset-stage-2": "6.5.0",
+    "babel-preset-stage-2": "6.11.0",
     "babel-register": "6.9.0",
     "bundle-loader": "0.5.4",
     "chai": "3.5.0",