fix(FEC-7528): multiple players cannot be loaded (#60)

since only one instance of babel-polyfill is allowed, we have to require babel-polyfill conditionally only if not already exist

src/index.js

@@ -1,5 +1,4 @@
 // @flow
-import 'babel-polyfill' // Important! must be first import to support older browsers compatibility
 import PolyfillManager from './polyfills/polyfill-manager'
 import './polyfills/all'
 import getLogger, {getLogLevel, setLogLevel, LogLevel} from './utils/logger'

src/polyfills/polyfill-manager.js

@@ -1,6 +1,10 @@
 // @flow
 import getLogger from '../utils/logger'
 
+if (!window._babelPolyfill){
+  require("babel-polyfill");
+}
+
 export default class PolyfillManager {
   static _polyfills: Array<Function> = [];
   static _logger: any = getLogger('PolyfillManager');