Add autosize coverage to spinning boxes benchmark

osu.Framework.Benchmarks/BenchmarkManySpinningBoxes.cs

···
 using BenchmarkDotNet.Attributes;
 using NUnit.Framework;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
+using osuTK;
 using osuTK.Graphics;
 
 namespace osu.Framework.Benchmarks
 {
     public class BenchmarkManySpinningBoxes : GameBenchmark
     {
+        private TestGame game;
+
         [Test]
         [Benchmark]
-        public void RunFrame() => RunSingleFrame();
+        public void RunFrame()
+        {
+            game.MainContent.AutoSizeAxes = Axes.None;
+            game.MainContent.RelativeSizeAxes = Axes.Both;
+            RunSingleFrame();
+        }
 
-        protected override Game CreateGame() => new TestGame();
+        [Test]
+        [Benchmark]
+        public void RunFrameWithAutoSize()
+        {
+            game.MainContent.RelativeSizeAxes = Axes.None;
+            game.MainContent.AutoSizeAxes = Axes.Both;
+            RunSingleFrame();
+        }
+
+        [Test]
+        [Benchmark]
+        public void RunFrameWithAutoSizeDuration()
+        {
+            game.MainContent.RelativeSizeAxes = Axes.None;
+            game.MainContent.AutoSizeAxes = Axes.Both;
+            game.MainContent.AutoSizeDuration = 100;
+            RunSingleFrame();
+        }
+
+        protected override Game CreateGame() => game = new TestGame();
 
         private class TestGame : Game
         {
+            public Container MainContent;
+
             protected override void LoadComplete()
             {
                 base.LoadComplete();
 
+                Add(MainContent = new Container());
+
                 for (int i = 0; i < 1000; i++)
                 {
                     var box = new Box
                     {
-                        RelativeSizeAxes = Axes.Both,
+                        Size = new Vector2(100),
                         Colour = Color4.Black
                     };
 
-                    Add(box);
+                    MainContent.Add(box);
 
                     box.Spin(200, RotationDirection.Clockwise);
                 }