feat(cypress): load babel-polyfill before starting

`cypress open` lacks some ES6 support (doesn't run the same chrome version as `cypress run`)

cypress/support/index.js

@@ -13,6 +13,9 @@
 // https://on.cypress.io/configuration
 // ***********************************************************
 
+// cypress lacks support for some method in `cypress open` mode (not same chrome version as in `cypress run`)
+import "babel-polyfill";
+
 // Import commands.js using ES2015 syntax:
 import "./commands";
 

package.json

@@ -86,6 +86,7 @@
     ]
   },
   "devDependencies": {
+    "babel-polyfill": "^6.26.0",
     "cors-anywhere": "^0.4.1",
     "cross-env": "^5.1.4",
     "cypress": "^2.1.0",

src/index.js

@@ -2,10 +2,6 @@ import React from "react";
 import ReactDOM from "react-dom";
 import { MuiThemeProvider, createMuiTheme } from "material-ui/styles";
 
-// cypress:open doesn't support the following, we need to pollyfill ...
-import "mdn-polyfills/Array.prototype.includes";
-import "mdn-polyfills/Object.entries";
-
 import "./index.css";
 import RootContainer from "./containers/RootContainer";
 import registerServiceWorker from "./registerServiceWorker";