Use React.lazy in Suspense fixture (#13834)

fixtures/unstable-async/suspense/src/components/App.js

@@ -1,20 +1,13 @@
-import React, {unstable_Suspense as Suspense, PureComponent} from 'react';
+import React, {lazy, unstable_Suspense as Suspense, PureComponent} from 'react';
 import {unstable_scheduleCallback} from 'scheduler';
 import {
   unstable_trace as trace,
   unstable_wrap as wrap,
 } from 'scheduler/tracing';
-import {createResource} from 'react-cache';
-import {cache} from '../cache';
 import Spinner from './Spinner';
 import ContributorListPage from './ContributorListPage';
 
-const UserPageResource = createResource(() => import('./UserPage'));
-
-function UserPageLoader(props) {
-  const UserPage = UserPageResource.read(cache).default;
-  return <UserPage {...props} />;
-}
+const UserPage = lazy(() => import('./UserPage'));
 
 export default class App extends PureComponent {
   state = {
@@ -77,7 +70,7 @@ export default class App extends PureComponent {
           Return to list
         </button>
         <Suspense maxDuration={2000} fallback={<Spinner size="large" />}>
-          <UserPageLoader id={id} />
+          <UserPage id={id} />
         </Suspense>
       </div>
     );