whoops flow types for new functions

Author: Colby Rabideau

src/isNull.js

@@ -6,6 +6,6 @@
  * @param  {any}  subject
  * @return {boolean}
  */
-export default function isNull(subject) {
+export default function isNull(subject: any) {
   return subject === null;
 }

src/isUndefined.js

@@ -6,6 +6,6 @@
  * @param  {any}  subject
  * @return {boolean}
  */
-export default function isUndefined(subject) {
+export default function isUndefined(subject: any) {
   return subject === undefined;
 }