Stop using the List constructor (#71957)

dev/benchmarks/macrobenchmarks/lib/src/heavy_grid_view.dart

@@ -19,7 +19,7 @@ class HeavyWidget extends StatelessWidget {
   HeavyWidget(this.index) : super(key: ValueKey<int>(index));
 
   final int index;
-  final List<int> _weight = List<int>(1000000);
+  final List<int> _weight = List<int>.filled(1000000, null);
 
   @override
   Widget build(BuildContext context) {

dev/tools/vitool/lib/vitool.dart

@@ -77,7 +77,7 @@ class PathAnimation {
     final List<PathCommandAnimation> commands = <PathCommandAnimation>[];
     for (int commandIdx = 0; commandIdx < frames[0].paths[pathIdx].commands.length; commandIdx += 1) {
       final int numPointsInCommand = frames[0].paths[pathIdx].commands[commandIdx].points.length;
-      final List<List<Point<double>>> points = List<List<Point<double>>>(numPointsInCommand);
+      final List<List<Point<double>>> points = List<List<Point<double>>>.filled(numPointsInCommand, null);
       for (int j = 0; j < numPointsInCommand; j += 1)
         points[j] = <Point<double>>[];
       final String commandType = frames[0].paths[pathIdx].commands[commandIdx].type;
@@ -422,7 +422,7 @@ class SvgPathCommandBuilder {
 }
 
 List<double> _pointsToVector3Array(List<Point<double>> points) {
-  final List<double> result = List<double>(points.length * 3);
+  final List<double> result = List<double>.filled(points.length * 3, null);
   for (int i = 0; i < points.length; i += 1) {
     result[i * 3] = points[i].x;
     result[i * 3 + 1] = points[i].y;
@@ -433,7 +433,7 @@ List<double> _pointsToVector3Array(List<Point<double>> points) {
 
 List<Point<double>> _vector3ArrayToPoints(List<double> vector) {
   final int numPoints = (vector.length / 3).floor();
-  final List<Point<double>> points = List<Point<double>>(numPoints);
+  final List<Point<double>> points = List<Point<double>>.filled(numPoints, null);
   for (int i = 0; i < numPoints; i += 1) {
     points[i] = Point<double>(vector[i*3], vector[i*3 + 1]);
   }

examples/image_list/lib/main.dart

@@ -178,14 +178,14 @@ class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
 
   @override
   Widget build(BuildContext context) {
-    final List<AnimationController> controllers = List<AnimationController>(IMAGES);
+    final List<AnimationController> controllers = List<AnimationController>.filled(IMAGES, null);
     for (int i = 0; i < IMAGES; i++) {
       controllers[i] = AnimationController(
         duration: const Duration(milliseconds: 3600),
         vsync: this,
       )..repeat();
     }
-    final List<Completer<bool>> completers = List<Completer<bool>>(IMAGES);
+    final List<Completer<bool>> completers = List<Completer<bool>>.filled(IMAGES, null);
     for (int i = 0; i < IMAGES; i++) {
       completers[i] = Completer<bool>();
     }