test: change fixturesDir to fixtures.path

PR-URL: https://github.com/nodejs/node/pull/15902
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-fs-read-stream-throw-type-error.js

@@ -1,10 +1,10 @@
 'use strict';
 const common = require('../common');
+const fixtures = require('../common/fixtures');
 const assert = require('assert');
 const fs = require('fs');
-const path = require('path');
 
-const example = path.join(common.fixturesDir, 'x.txt');
+const example = fixtures.path('x.txt');
 
 assert.doesNotThrow(function() {
   fs.createReadStream(example, undefined);