UIExplorer flowification

Examples/UIExplorer/GeolocationExample.js

@@ -1,5 +1,6 @@
 /**
  * Copyright 2004-present Facebook. All Rights Reserved.
+ * @flow
  */
 /* eslint no-console: 0 */
 'use strict';
@@ -19,13 +20,15 @@ exports.description = 'Examples of using the Geolocation API.';
 exports.examples = [
   {
     title: 'navigator.geolocation',
-    render: function() {
+    render: function(): ReactElement {
       return <GeolocationExample />;
     },
   }
 ];
 
 var GeolocationExample = React.createClass({
+  watchID: (null: ?number),
+
   getInitialState: function() {
     return {
       initialPosition: 'unknown',