Index: frontend/node_modules/react-app-polyfill/ie9.js
===================================================================
--- frontend/node_modules/react-app-polyfill/ie9.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
+++ frontend/node_modules/react-app-polyfill/ie9.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+'use strict';
+
+require('./ie11');
+
+// React 16+ relies on Map, Set, and requestAnimationFrame
+require('core-js/features/map');
+require('core-js/features/set');
+
+require('raf').polyfill();