test: increase coverage for timers

Add a test for cancelling timers with null or no arguments.

PR-URL: https://github.com/nodejs/node/pull/10068
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

test/parallel/test-timers-clear-null-does-not-throw-error.js

@@ -0,0 +1,18 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+
+// This test makes sure clearing timers with
+// 'null' or no input does not throw error
+
+assert.doesNotThrow(() => clearInterval(null));
+
+assert.doesNotThrow(() => clearInterval());
+
+assert.doesNotThrow(() => clearTimeout(null));
+
+assert.doesNotThrow(() => clearTimeout());
+
+assert.doesNotThrow(() => clearImmediate(null));
+
+assert.doesNotThrow(() => clearImmediate());