chore(devenv): load polyfill into Storybook env (carbon-design-system…

…#548)

* chore(devenv): load polyfill into Storybook env

Refs carbon-design-system#533.

* docs(polyfills): update README for polyfills

.storybook/Container.js

@@ -1,4 +1,5 @@
 import React, { Component } from 'react';
+import './polyfills';
 import './_container.scss';
 
 export default class Container extends Component {

.storybook/polyfills.js

@@ -0,0 +1,4 @@
+import 'core-js/modules/es7.array.includes';
+import 'core-js/modules/es6.array.fill';
+import 'core-js/modules/es6.string.includes';
+import 'core-js/modules/es6.string.trim';

README.md

@@ -25,6 +25,8 @@ npm install -S carbon-components-react carbon-components carbon-icons
 
 2. Components do not import any of the styles themselves, use the scss or css from `carbon-components` to bring in styling. You can also use the `unpkg` cdn to bring in the styles wholesale - `unpkg.com/carbon-components/css/carbon-components.css` aliases the latest css file.
 
+3. For older browsers (e.g. IE11), polyfills listed in [`carbon-components-react/.storybook/polyfills.js` file](./.storybook/polyfills.js) is required.
+
 ## Development
 
 Please refer to the [Contribution Guidelines](CONTRIBUTING.md) before starting any work.