Remove new keyword from default template app (#22454)

* Remove new keyword from default template app

packages/flutter_tools/templates/app/lib/main.dart.tmpl

@@ -10,14 +10,14 @@ import 'package:{{pluginProjectName}}/{{pluginProjectName}}.dart';
 {{/withPluginHook}}
 
 {{^withDriverTest}}
-void main() => runApp(new MyApp());
+void main() => runApp(MyApp());
 {{/withDriverTest}}
 {{#withDriverTest}}
 void main() {
   // Enable integration testing with the Flutter Driver extension.
   // See https://flutter.io/testing/ for more info.
   enableFlutterDriverExtension();
-  runApp(new MyApp());
+  runApp(MyApp());
 }
 {{/withDriverTest}}
 
@@ -26,9 +26,9 @@ class MyApp extends StatelessWidget {
   // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {
-    return new MaterialApp(
+    return MaterialApp(
       title: 'Flutter Demo',
-      theme: new ThemeData(
+      theme: ThemeData(
         // This is the theme of your application.
         //
         // Try running your application with "flutter run". You'll see the
@@ -39,7 +39,7 @@ class MyApp extends StatelessWidget {
         // counter didn't reset back to zero; the application is not restarted.
         primarySwatch: Colors.blue,
       ),
-      home: new MyHomePage(title: 'Flutter Demo Home Page'),
+      home: MyHomePage(title: 'Flutter Demo Home Page'),
     );
   }
 }
@@ -59,7 +59,7 @@ class MyHomePage extends StatefulWidget {
   final String title;
 
   @override
-  _MyHomePageState createState() => new _MyHomePageState();
+  _MyHomePageState createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {
@@ -84,16 +84,16 @@ class _MyHomePageState extends State<MyHomePage> {
     // The Flutter framework has been optimized to make rerunning build methods
     // fast, so that you can just rebuild anything that needs updating rather
     // than having to individually change instances of widgets.
-    return new Scaffold(
-      appBar: new AppBar(
+    return Scaffold(
+      appBar: AppBar(
         // Here we take the value from the MyHomePage object that was created by
         // the App.build method, and use it to set our appbar title.
-        title: new Text(widget.title),
+        title: Text(widget.title),
       ),
-      body: new Center(
+      body: Center(
         // Center is a layout widget. It takes a single child and positions it
         // in the middle of the parent.
-        child: new Column(
+        child: Column(
           // Column is also layout widget. It takes a list of children and
           // arranges them vertically. By default, it sizes itself to fit its
           // children horizontally, and tries to be as tall as its parent.
@@ -109,20 +109,20 @@ class _MyHomePageState extends State<MyHomePage> {
           // horizontal).
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
-            new Text(
+            Text(
               'You have pushed the button this many times:',
             ),
-            new Text(
+            Text(
               '$_counter',
               style: Theme.of(context).textTheme.display1,
             ),
           ],
         ),
       ),
-      floatingActionButton: new FloatingActionButton(
+      floatingActionButton: FloatingActionButton(
         onPressed: _incrementCounter,
         tooltip: 'Increment',
-        child: new Icon(Icons.add),
+        child: Icon(Icons.add),
       ), // This trailing comma makes auto-formatting nicer for build methods.
     );
   }
@@ -131,7 +131,7 @@ class _MyHomePageState extends State<MyHomePage> {
 {{#withPluginHook}}
 class MyApp extends StatefulWidget {
   @override
-  _MyAppState createState() => new _MyAppState();
+  _MyAppState createState() => _MyAppState();
 }
 
 class _MyAppState extends State<MyApp> {
@@ -165,13 +165,13 @@ class _MyAppState extends State<MyApp> {
 
   @override
   Widget build(BuildContext context) {
-    return new MaterialApp(
-      home: new Scaffold(
-        appBar: new AppBar(
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(
           title: const Text('Plugin example app'),
         ),
-        body: new Center(
-          child: new Text('Running on: $_platformVersion\n'),
+        body: Center(
+          child: Text('Running on: $_platformVersion\n'),
         ),
       ),
     );