test: remove test-cluster-* var redeclarations

PR-URL: #4980
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

test/parallel/test-cluster-bind-twice.js

@@ -51,7 +51,7 @@ if (!id) {
     b.send('START');
   });
 
-  var ok = false;
+  let ok = false;
 
   b.on('message', function(m) {
     if (typeof m === 'object') return; // ignore system messages
@@ -68,7 +68,7 @@ if (!id) {
 else if (id === 'one') {
   if (cluster.isMaster) return startWorker();
 
-  var server = http.createServer(common.fail).listen(common.PORT, function() {
+  http.createServer(common.fail).listen(common.PORT, function() {
     process.send('READY');
   });
 
@@ -79,7 +79,7 @@ else if (id === 'one') {
 else if (id === 'two') {
   if (cluster.isMaster) return startWorker();
 
-  var ok = false;
+  let ok = false;
   process.on('exit', function() {
     assert(ok);
   });

test/parallel/test-cluster-dgram-2.js

@@ -20,7 +20,6 @@ else
 
 
 function master() {
-  var i;
   var received = 0;
 
   // Start listening on a socket.

test/parallel/test-cluster-eaddrinuse.js

@@ -11,7 +11,7 @@ var net = require('net');
 var id = '' + process.argv[2];
 
 if (id === 'undefined') {
-  var server = net.createServer(common.fail);
+  const server = net.createServer(common.fail);
   server.listen(common.PORT, function() {
     var worker = fork(__filename, ['worker']);
     worker.on('message', function(msg) {
@@ -23,7 +23,7 @@ if (id === 'undefined') {
   });
 }
 else if (id === 'worker') {
-  var server = net.createServer(common.fail);
+  let server = net.createServer(common.fail);
   server.listen(common.PORT, common.fail);
   server.on('error', common.mustCall(function(e) {
     assert(e.code, 'EADDRINUSE');