Unnecessary new (#20138)

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests
diff --git a/examples/layers/widgets/media_query.dart b/examples/layers/widgets/media_query.dart
index ef929b8..69ed7f3 100644
--- a/examples/layers/widgets/media_query.dart
+++ b/examples/layers/widgets/media_query.dart
@@ -11,15 +11,15 @@
 
   @override
   Widget build(BuildContext context) {
-    return new Row(
+    return Row(
       children: <Widget>[
-        new Container(
+        Container(
           width: 32.0,
           height: 32.0,
           margin: const EdgeInsets.all(8.0),
           color: Colors.lightBlueAccent.shade100,
         ),
-        new Text(name)
+        Text(name)
       ]
     );
   }
@@ -32,20 +32,20 @@
 
   @override
   Widget build(BuildContext context) {
-    return new Card(
-      child: new Column(
+    return Card(
+      child: Column(
         children: <Widget>[
-          new Expanded(
-            child: new Container(
+          Expanded(
+            child: Container(
               color: Colors.lightBlueAccent.shade100,
             )
           ),
-          new Container(
+          Container(
             margin: const EdgeInsets.only(left: 8.0),
-            child: new Row(
+            child: Row(
               children: <Widget>[
-                new Expanded(
-                  child: new Text(name)
+                Expanded(
+                  child: Text(name)
                 ),
                 const IconButton(
                   icon: Icon(Icons.more_vert),
@@ -72,14 +72,14 @@
   @override
   Widget build(BuildContext context) {
     if (MediaQuery.of(context).size.width < _kGridViewBreakpoint) {
-      return new ListView(
+      return ListView(
         itemExtent: _kListItemExtent,
-        children: names.map((String name) => new AdaptedListItem(name: name)).toList(),
+        children: names.map((String name) => AdaptedListItem(name: name)).toList(),
       );
     } else {
-      return new GridView.extent(
+      return GridView.extent(
         maxCrossAxisExtent: _kMaxTileWidth,
-        children: names.map((String name) => new AdaptedGridItem(name: name)).toList(),
+        children: names.map((String name) => AdaptedGridItem(name: name)).toList(),
       );
     }
   }
@@ -95,13 +95,13 @@
 final List<String> _kNames = _initNames();
 
 void main() {
-  runApp(new MaterialApp(
+  runApp(MaterialApp(
     title: 'Media Query Example',
-    home: new Scaffold(
-      appBar: new AppBar(
+    home: Scaffold(
+      appBar: AppBar(
         title: const Text('Media Query Example')
       ),
-      body: new Material(child: new AdaptiveContainer(names: _kNames))
+      body: Material(child: AdaptiveContainer(names: _kNames))
     )
   ));
 }