benchmark: convert var to es6 const

Converted var variable to es6 const to maintain
consistency with other benchmark files. Also clean up
the types array to make the files more succinct.

PR-URL: https://github.com/nodejs/node/pull/12886
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

benchmark/arrays/var-int.js

@@ -1,7 +1,8 @@
 'use strict';
-var common = require('../common.js');
+const common = require('../common.js');
 
-var types = [
+const bench = common.createBenchmark(main, {
+  type: [
     'Array',
     'Buffer',
     'Int8Array',
@@ -12,17 +13,14 @@ var types = [
     'Uint32Array',
     'Float32Array',
     'Float64Array'
-];
-
-var bench = common.createBenchmark(main, {
-  type: types,
+  ],
   n: [25]
 });
 
 function main(conf) {
-  var type = conf.type;
-  var clazz = global[type];
-  var n = +conf.n;
+  const type = conf.type;
+  const clazz = global[type];
+  const n = +conf.n;
 
   bench.start();
   var arr = new clazz(n * 1e6);

benchmark/arrays/zero-float.js

@@ -1,7 +1,8 @@
 'use strict';
-var common = require('../common.js');
+const common = require('../common.js');
 
-var types = [
+const bench = common.createBenchmark(main, {
+  type: [
     'Array',
     'Buffer',
     'Int8Array',
@@ -12,17 +13,14 @@ var types = [
     'Uint32Array',
     'Float32Array',
     'Float64Array'
-];
-
-var bench = common.createBenchmark(main, {
-  type: types,
+  ],
   n: [25]
 });
 
 function main(conf) {
-  var type = conf.type;
-  var clazz = global[type];
-  var n = +conf.n;
+  const type = conf.type;
+  const clazz = global[type];
+  const n = +conf.n;
 
   bench.start();
   var arr = new clazz(n * 1e6);

benchmark/arrays/zero-int.js

@@ -1,7 +1,8 @@
 'use strict';
-var common = require('../common.js');
+const common = require('../common.js');
 
-var types = [
+const bench = common.createBenchmark(main, {
+  type: [
     'Array',
     'Buffer',
     'Int8Array',
@@ -12,17 +13,14 @@ var types = [
     'Uint32Array',
     'Float32Array',
     'Float64Array'
-];
-
-var bench = common.createBenchmark(main, {
-  type: types,
+  ],
   n: [25]
 });
 
 function main(conf) {
-  var type = conf.type;
-  var clazz = global[type];
-  var n = +conf.n;
+  const type = conf.type;
+  const clazz = global[type];
+  const n = +conf.n;
 
   bench.start();
   var arr = new clazz(n * 1e6);