Issue 4795 - Use modern JavaScript syntax

qunit/tests/cssEscaping.js

 "use strict";
 
 {
-  let {Filter, ElemHideFilter} = require("filterClasses");
-  let {escapeCSS, quoteCSS} = require("filterComposer");
+  const {Filter, ElemHideFilter} = require("filterClasses");
+  const {escapeCSS, quoteCSS} = require("filterComposer");
 
   module("CSS escaping");
 
   test("CSS escaping", () =>
   {
     function testSelector(opts)
     {
       let mustMatch = opts.mustMatch !== false;
       let doc = document.implementation.createHTMLDocument();
 
@@ skipping 80 matching lines @@
       testEscape("x" + chr);
 
       // Leading dashes must be escaped, when followed by certain characters.
       testEscape("-" + chr);
     }
 
     // Test some non-ASCII characters. However, those shouldn't require escaping.
     testEscape("\uD83D\uDE3B\u2665\u00E4");
   });
 }