Izmjenjena struktura, dodan backand

web/node_modules/core-js/modules/$.enum-keys.js

@@ -0,0 +1,14 @@
+// all enumerable object keys, includes symbols
+var $ = require('./$');
+module.exports = function(it){
+  var keys       = $.getKeys(it)
+    , getSymbols = $.getSymbols;
+  if(getSymbols){
+    var symbols = getSymbols(it)
+      , isEnum  = $.isEnum
+      , i       = 0
+      , key;
+    while(symbols.length > i)if(isEnum.call(it, key = symbols[i++]))keys.push(key);
+  }
+  return keys;
+};