Configring node js.

node_modules/core-js/modules/_collection-to-json.js

@@ -0,0 +1,9 @@
+// https://github.com/DavidBruant/Map-Set.prototype.toJSON
+var classof = require('./_classof')
+  , from    = require('./_array-from-iterable');
+module.exports = function(NAME){
+  return function toJSON(){
+    if(classof(this) != NAME)throw TypeError(NAME + "#toJSON isn't generic");
+    return from(this);
+  };
+};