Flutter 去除右上角角标

• Flutter 默认创建应用程序右上角会自带一个 DEBUG 的角标，在如下代码添加
  debugShowCheckedModeBanner: false, 即可去除

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter'),
    );
  }
}