Update dependency chromedriver to v2.40.0 (#339)

Author: renovate[bot]

package-lock.json

@@ -38,7 +38,7 @@
   },
   "devDependencies": {
     "chalk": "2.4.1",
-    "chromedriver": "2.33.2",
+    "chromedriver": "2.40.0",
     "del": "3.0.0",
     "eslint": "4.12.1",
     "eslint-config-airbnb": "16.1.0",