add all frontend files

node_modules/es-abstract/2017/ToString.js

@@ -0,0 +1,15 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $String = GetIntrinsic('%String%');
+var $TypeError = require('es-errors/type');
+
+// https://262.ecma-international.org/6.0/#sec-tostring
+
+module.exports = function ToString(argument) {
+	if (typeof argument === 'symbol') {
+		throw new $TypeError('Cannot convert a Symbol value to a string');
+	}
+	return $String(argument);
+};