test: update test/parallel/test-eval.js

Changed var -> const and assert.equal -> assert.strictEqual

PR-URL: https://github.com/nodejs/node/pull/8590
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-eval.js

@@ -1,13 +1,13 @@
 'use strict';
 const common = require('../common');
-var util = require('util');
-var assert = require('assert');
-var exec = require('child_process').exec;
+const util = require('util');
+const assert = require('assert');
+const exec = require('child_process').exec;
 
-var cmd = ['"' + process.execPath + '"', '-e', '"console.error(process.argv)"',
-           'foo', 'bar'].join(' ');
-var expected = util.format([process.execPath, 'foo', 'bar']) + '\n';
+const cmd = ['"' + process.execPath + '"', '-e',
+             '"console.error(process.argv)"', 'foo', 'bar'].join(' ');
+const expected = util.format([process.execPath, 'foo', 'bar']) + '\n';
 exec(cmd, common.mustCall(function(err, stdout, stderr) {
   assert.ifError(err);
-  assert.equal(stderr, expected);
+  assert.strictEqual(stderr, expected);
 }));