Update babel7 to the latest version 🚀 (#950)

* chore(package): update @babel/core to version 7.6.4

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -36,7 +36,7 @@
     "xmlhttprequest": "1.8.0"
   },
   "devDependencies": {
-    "@babel/core": "7.6.3",
+    "@babel/core": "7.6.4",
     "@babel/plugin-proposal-class-properties": "7.5.5",
     "@babel/plugin-transform-flow-comments": "7.6.3",
     "@babel/plugin-transform-flow-strip-types": "7.6.3",