Source: polyfills/CustomEvent.js

/**
 * {@link https://github.com/webcomponents/webcomponentsjs/commit/8d6a38aa6e3d03ff54a41db9e9725401bbc1446c Strange commit, checks CustomEvent only in IE}
 * @constructor CustomEvent
 * @see https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent
 */
import context from '../context';
import CustomEventCommon from './CustomEventCommon';
if (typeof context.CustomEvent !== 'function') {
    context.CustomEvent = CustomEventCommon;
}