Configring node js.

node_modules/core-js/modules/_enum-keys.js

@@ -0,0 +1,15 @@
+// all enumerable object keys, includes symbols
+var getKeys = require('./_object-keys')
+  , gOPS    = require('./_object-gops')
+  , pIE     = require('./_object-pie');
+module.exports = function(it){
+  var result     = getKeys(it)
+    , getSymbols = gOPS.f;
+  if(getSymbols){
+    var symbols = getSymbols(it)
+      , isEnum  = pIE.f
+      , i       = 0
+      , key;
+    while(symbols.length > i)if(isEnum.call(it, key = symbols[i++]))result.push(key);
+  } return result;
+};