benchmark: use strict mode

Apply strict mode to benchmark code.

PR-URL: #5336
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: Trott

benchmark/arrays/var-int.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 var bench = common.createBenchmark(main, {
   type: 'Array Buffer Int8Array Uint8Array Int16Array Uint16Array Int32Array Uint32Array Float32Array Float64Array'.split(' '),

benchmark/arrays/zero-float.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 var bench = common.createBenchmark(main, {
   type: 'Array Buffer Int8Array Uint8Array Int16Array Uint16Array Int32Array Uint32Array Float32Array Float64Array'.split(' '),

benchmark/arrays/zero-int.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 var bench = common.createBenchmark(main, {
   type: 'Array Buffer Int8Array Uint8Array Int16Array Uint16Array Int32Array Uint32Array Float32Array Float64Array'.split(' '),

benchmark/buffers/buffer-base64-decode.js

@@ -1,3 +1,4 @@
+'use strict';
 var assert = require('assert');
 var common = require('../common.js');
 

benchmark/buffers/buffer-base64-encode.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 
 var bench = common.createBenchmark(main, {});

benchmark/buffers/buffer-bytelength.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common');
 
 var bench = common.createBenchmark(main, {

benchmark/buffers/buffer-compare.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 
 var bench = common.createBenchmark(main, {

benchmark/buffers/buffer-creation.js

@@ -1,4 +1,5 @@
-SlowBuffer = require('buffer').SlowBuffer;
+'use strict';
+const SlowBuffer = require('buffer').SlowBuffer;
 
 var common = require('../common.js');
 var bench = common.createBenchmark(main, {

benchmark/buffers/buffer-indexof.js

@@ -1,3 +1,4 @@
+'use strict';
 var common = require('../common.js');
 var fs = require('fs');
 

benchmark/buffers/buffer-iterate.js

@@ -1,3 +1,4 @@
+'use strict';
 var SlowBuffer = require('buffer').SlowBuffer;
 var common = require('../common.js');
 var assert = require('assert');