added closest polyfill

Author: friedt

package.json

@@ -51,7 +51,8 @@
     "webpack-cli": "^3.3.10"
   },
   "dependencies": {
-    "core-js": "^3.6.0"
+    "core-js": "^3.6.0",
+    "element-closest-polyfill": "^1.0.0"
   },
   "repository": {
     "type": "git",

src/javascript/index.js

@@ -1,4 +1,6 @@
-import 'core-js/es/array/from'; // polyfill IE11
+import 'core-js/es/array/from'; // polyfill IE10/11
+import 'element-closest-polyfill'; // polyfill IE10/11
+
 import {initProgressBar} from './progress-bar';
 
 // get nodelist to bind to the progress-bar