added whole system from ola4doc

sys/node_modules/es5-ext/date/valid-date.js

@@ -0,0 +1,8 @@
+'use strict';
+
+var isDate = require('./is-date');
+
+module.exports = function (x) {
+	if (!isDate(x) || isNaN(x)) throw new TypeError(x + " is not valid Date object");
+	return x;
+};