test: replaces common.fixturesDir usage

In test/parallel/test-repl-require.js replaces usage of
common.fixturesDir with common/fixtures.

Part of Node.js Interactive 2017 Code & Learn

PR-URL: #15818
Reviewed-By: Ryan Graham <r.m.graham@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

test/parallel/test-repl-require.js

@@ -1,10 +1,11 @@
 'use strict';
 
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 const assert = require('assert');
 const net = require('net');
 
-process.chdir(common.fixturesDir);
+process.chdir(fixtures.fixturesDir);
 const repl = require('repl');
 
 const server = net.createServer((conn) => {