Revert "Merge pull request #267 from unexpectedjs/depfu/update/npm/js…

…dom-15.0.0"

This reverts commit 573aa29, reversing
changes made to 024cb73.

package.json

@@ -56,7 +56,7 @@
     "eslint-plugin-prettier": "^3.0.0",
     "gh-pages": "^2.0.1",
     "istanbul": "^0.4.5",
-    "jsdom": "^15.0.0",
+    "jsdom": "^14.0.0",
     "karma": "^4.1.0",
     "karma-browserstack-launcher": "1.4.0",
     "karma-chrome-launcher": "^2.2.0",