add all frontend files

node_modules/es-abstract/2017/abs.js

@@ -0,0 +1,9 @@
+'use strict';
+
+var $abs = require('math-intrinsics/abs');
+
+// https://262.ecma-international.org/5.1/#sec-5.2
+
+module.exports = function abs(x) {
+	return $abs(x);
+};