chore(HomeView): use cleaner syntax to define flow prop types

src/views/HomeView/HomeView.js

@@ -21,7 +21,8 @@ type Props = {
 // We avoid using the `@connect` decorator on the class definition so
 // that we can export the undecorated component for testing.
 // See: http://rackt.github.io/redux/docs/recipes/WritingTests.html
-export class HomeView extends React.Component<void, Props, void> {
+export class HomeView extends React.Component {
+  props: Props;
   static propTypes = {
     counter: PropTypes.number.isRequired,
     doubleAsync: PropTypes.func.isRequired,