add all frontend files

node_modules/es-abstract/2024/SystemTimeZoneIdentifier.js

@@ -0,0 +1,18 @@
+'use strict';
+
+var callBind = require('call-bind');
+
+var I402 = typeof Intl === 'undefined' ? null : Intl;
+var DateTimeFormat = !!I402 && I402.DateTimeFormat;
+var resolvedOptions = !!DateTimeFormat && callBind(DateTimeFormat.prototype.resolvedOptions);
+
+// https://262.ecma-international.org/15.0/#sec-systemtimezoneidentifier
+
+module.exports = function SystemTimeZoneIdentifier() {
+	if (DateTimeFormat && resolvedOptions) {
+		return resolvedOptions(new DateTimeFormat()).timeZone; // steps 2 - 3
+
+	}
+
+	return 'UTC'; // step 1
+};