all these changes

frontend/node_modules/core-js/internals/set-clone.js

@@ -0,0 +1,14 @@
+'use strict';
+var SetHelpers = require('../internals/set-helpers');
+var iterate = require('../internals/set-iterate');
+
+var Set = SetHelpers.Set;
+var add = SetHelpers.add;
+
+module.exports = function (set) {
+  var result = new Set();
+  iterate(set, function (it) {
+    add(result, it);
+  });
+  return result;
+};