Fixed types of onRequestClose argument.

This is defined as being native events, but are actually Synthetic events.

See https://github.com/reactjs/react-modal/blob/988f55a277373d119a4c37e7d4cce7e681147326/src/components/ModalPortal.js

types/react-modal/index.d.ts

@@ -68,7 +68,7 @@ declare namespace ReactModal {
         onAfterClose?(): void;
 
         /* Function that will be run when the modal is requested to be closed, prior to actually closing. */
-        onRequestClose?(event: (MouseEvent | KeyboardEvent)): void;
+        onRequestClose?(event: (React.MouseEvent | React.KeyboardEvent)): void;
 
         /* Number indicating the milliseconds to wait before closing the modal. Defaults to zero (no timeout). */
         closeTimeoutMS?: number;

types/react-modal/react-modal-tests.tsx

@@ -13,7 +13,7 @@ class ExampleOfUsingReactModal extends React.Component {
   render() {
     const onAfterOpenFn = () => { };
     const onAfterCloseFn = () => { };
-    const onRequestCloseFn = () => { };
+    const onRequestCloseFn = (event: React.MouseEvent | React.KeyboardEvent) => { };
     const customStyle = {
       overlay: {
         position: 'fixed',