chore(package): update babel-plugin-transform-class-properties to version 6.18.0 (#533)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -42,7 +42,7 @@
     "babel-eslint": "7.1.0",
     "babel-plugin-check-es2015-constants": "6.8.0",
     "babel-plugin-syntax-async-functions": "6.13.0",
-    "babel-plugin-transform-class-properties": "6.16.0",
+    "babel-plugin-transform-class-properties": "6.18.0",
     "babel-plugin-transform-es2015-arrow-functions": "6.8.0",
     "babel-plugin-transform-es2015-block-scoped-functions": "6.8.0",
     "babel-plugin-transform-es2015-block-scoping": "6.18.0",