test: add regression tests

This makes sure util.isDate and util.isRegExp will not abort in case
more than one argument is passed to the utility function.

PR-URL: nodejs#19188
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-util.js

@@ -42,7 +42,7 @@ assert.strictEqual(false, util.isArray(Object.create(Array.prototype)));
 
 // isRegExp
 assert.strictEqual(true, util.isRegExp(/regexp/));
-assert.strictEqual(true, util.isRegExp(RegExp()));
+assert.strictEqual(true, util.isRegExp(RegExp(), 'foo'));
 assert.strictEqual(true, util.isRegExp(new RegExp()));
 assert.strictEqual(true, util.isRegExp(context('RegExp')()));
 assert.strictEqual(false, util.isRegExp({}));
@@ -52,7 +52,7 @@ assert.strictEqual(false, util.isRegExp(Object.create(RegExp.prototype)));
 
 // isDate
 assert.strictEqual(true, util.isDate(new Date()));
-assert.strictEqual(true, util.isDate(new Date(0)));
+assert.strictEqual(true, util.isDate(new Date(0), 'foo'));
 assert.strictEqual(true, util.isDate(new (context('Date'))()));
 assert.strictEqual(false, util.isDate(Date()));
 assert.strictEqual(false, util.isDate({}));