benchmark: use let instead of var in tls

PR-URL: https://github.com/nodejs/node/pull/31794
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

benchmark/tls/convertprotocols.js

@@ -9,7 +9,7 @@ const bench = common.createBenchmark(main, {
 
 function main({ n }) {
   const input = ['ABC', 'XYZ123', 'FOO'];
-  var m = {};
+  let m = {};
   // First call dominates results
   if (n > 1) {
     tls.convertALPNProtocols(input, m);

benchmark/tls/throughput.js

@@ -7,12 +7,12 @@ const bench = common.createBenchmark(main, {
 });
 
 const fixtures = require('../../test/common/fixtures');
-var options;
+let options;
 const tls = require('tls');
 
 function main({ dur, type, size }) {
-  var encoding;
-  var chunk;
+  let encoding;
+  let chunk;
   switch (type) {
     case 'buf':
       chunk = Buffer.alloc(size, 'b');
@@ -37,7 +37,7 @@ function main({ dur, type, size }) {
   };
 
   const server = tls.createServer(options, onConnection);
-  var conn;
+  let conn;
   server.listen(common.PORT, () => {
     const opt = { port: common.PORT, rejectUnauthorized: false };
     conn = tls.connect(opt, () => {
@@ -52,7 +52,7 @@ function main({ dur, type, size }) {
     }
   });
 
-  var received = 0;
+  let received = 0;
   function onConnection(conn) {
     conn.on('data', (chunk) => {
       received += chunk.length;

benchmark/tls/tls-connect.js

@@ -8,11 +8,11 @@ const bench = common.createBenchmark(main, {
   dur: [5]
 });
 
-var clientConn = 0;
-var serverConn = 0;
-var dur;
-var concurrency;
-var running = true;
+let clientConn = 0;
+let serverConn = 0;
+let dur;
+let concurrency;
+let running = true;
 
 function main(conf) {
   dur = conf.dur;