[Flow] Fix or suppress errors in react-native for Flow v0.13.0

Examples/UIExplorer/WebViewExample.js

@@ -220,6 +220,7 @@ var styles = StyleSheet.create({
   },
 });
 
+exports.displayName = (undefined: ?string);
 exports.title = '<WebView>';
 exports.description = 'Base component to display web content';
 exports.examples = [