Added the underscore node_module.

node_modules/underscore/modules/underscore.js

@@ -0,0 +1,25 @@
+import { VERSION } from './_setup.js';
+
+// If Underscore is called as a function, it returns a wrapped object that can
+// be used OO-style. This wrapper holds altered versions of all functions added
+// through `_.mixin`. Wrapped objects may be chained.
+export default function _(obj) {
+  if (obj instanceof _) return obj;
+  if (!(this instanceof _)) return new _(obj);
+  this._wrapped = obj;
+}
+
+_.VERSION = VERSION;
+
+// Extracts the result from a wrapped and chained object.
+_.prototype.value = function() {
+  return this._wrapped;
+};
+
+// Provide unwrapping proxies for some methods used in engine operations
+// such as arithmetic and JSON stringification.
+_.prototype.valueOf = _.prototype.toJSON = _.prototype.value;
+
+_.prototype.toString = function() {
+  return String(this._wrapped);
+};