Migrate to Babel env preset

.babelrc

@@ -4,7 +4,9 @@
     "transform-object-rest-spread"
   ],
   "presets": [
-    ["es2015", { "modules": false }],
+    ["env", {
+      "modules": false
+    }],
     "stage-0"
   ]
 }

package.json

@@ -20,7 +20,7 @@
     "babel-plugin-transform-class-properties": "^6.24.1",
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-plugin-transform-runtime": "^6.23.0",
-    "babel-preset-es2015": "^6.24.1",
+    "babel-preset-env": "1.6.1",
     "babel-preset-stage-0": "^6.24.1",
     "babel-runtime": "^6.26.0",
     "case-sensitive-paths-webpack-plugin": "^2.1.1",