chore(package): update babel-preset-es2015 to version 6.24.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -35,7 +35,7 @@
     "babel-cli": "^6.8.0",
     "babel-core": "^6.7.7",
     "babel-plugin-istanbul": "^4.0.0",
-    "babel-preset-es2015": "^6.6.0",
+    "babel-preset-es2015": "^6.24.0",
     "babel-register": "^6.11.5",
     "chai": "^3.5.0",
     "chokidar-cli": "^1.2.0",