Unnecessary new (#20138)

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

examples/layers/rendering/custom_coordinate_systems.dart

diff --git a/examples/layers/rendering/custom_coordinate_systems.dart b/examples/layers/rendering/custom_coordinate_systems.dart
index c1dd8ce..208bcf1 100644
--- a/examples/layers/rendering/custom_coordinate_systems.dart
+++ b/examples/layers/rendering/custom_coordinate_systems.dart
@@ -9,17 +9,17 @@
 import 'src/sector_layout.dart';
 
 RenderBox buildSectorExample() {
-  final RenderSectorRing rootCircle = new RenderSectorRing(padding: 20.0);
-  rootCircle.add(new RenderSolidColor(const Color(0xFF00FFFF), desiredDeltaTheta: kTwoPi * 0.15));
-  rootCircle.add(new RenderSolidColor(const Color(0xFF0000FF), desiredDeltaTheta: kTwoPi * 0.4));
-  final RenderSectorSlice stack = new RenderSectorSlice(padding: 2.0);
-  stack.add(new RenderSolidColor(const Color(0xFFFFFF00), desiredDeltaRadius: 20.0));
-  stack.add(new RenderSolidColor(const Color(0xFFFF9000), desiredDeltaRadius: 20.0));
-  stack.add(new RenderSolidColor(const Color(0xFF00FF00)));
+  final RenderSectorRing rootCircle = RenderSectorRing(padding: 20.0);
+  rootCircle.add(RenderSolidColor(const Color(0xFF00FFFF), desiredDeltaTheta: kTwoPi * 0.15));
+  rootCircle.add(RenderSolidColor(const Color(0xFF0000FF), desiredDeltaTheta: kTwoPi * 0.4));
+  final RenderSectorSlice stack = RenderSectorSlice(padding: 2.0);
+  stack.add(RenderSolidColor(const Color(0xFFFFFF00), desiredDeltaRadius: 20.0));
+  stack.add(RenderSolidColor(const Color(0xFFFF9000), desiredDeltaRadius: 20.0));
+  stack.add(RenderSolidColor(const Color(0xFF00FF00)));
   rootCircle.add(stack);
-  return new RenderBoxToRenderSectorAdapter(innerRadius: 50.0, child: rootCircle);
+  return RenderBoxToRenderSectorAdapter(innerRadius: 50.0, child: rootCircle);
 }
 
 void main() {
-  new RenderingFlutterBinding(root: buildSectorExample());
+  RenderingFlutterBinding(root: buildSectorExample());
 }