use modern js let

Author: Steven Yeh

assets/js/openrct2.website.js

@@ -1,4 +1,4 @@
-var openrct2 = {};
+let openrct2 = {};
 
 openrct2.Platform = Object.freeze({
     UNKNOWN: {},
@@ -30,7 +30,7 @@ openrct2.Platform = Object.freeze({
 
 function getPlatform() {
     if (navigator.platform.indexOf('Win') >= 0) {
-        if (navigator.userAgent.indexOf("WOW64") === -1 && navigator.userAgent.indexOf("Win64") === -1 ) {
+        if (navigator.userAgent.indexOf("WOW64") === -1 && navigator.userAgent.indexOf("Win64") === -1) {
             return openrct2.Platform.WINDOWS32;
         } else {
             return openrct2.Platform.WINDOWS64;  // 64-bit is the default as it is by far the most common these days