Fix incorrect defaults when adding non-BindableObject as AbsoluteLayout child

src/Controls/src/Core/Layout/AbsoluteLayout.cs

@@ -154,6 +154,11 @@ protected override void OnUpdate(int index, IView view, IView oldView)
 
 		class AbsoluteLayoutInfo
 		{
+			public AbsoluteLayoutInfo()
+			{
+				LayoutBounds = new Rect(0, 0, AutoSize, AutoSize);
+			}
+
 			public AbsoluteLayoutFlags LayoutFlags { get; set; }
 			public Rect LayoutBounds { get; set; }
 		}

src/Controls/tests/Core.UnitTests/Layouts/AbsoluteLayoutTests.cs

@@ -0,0 +1,64 @@
+#nullable enable
+using Xunit;
+
+namespace Microsoft.Maui.Controls.Core.UnitTests.Layouts
+{
+	[Category("Layout")]
+	public class AbsoluteLayoutTests : BaseTestFixture 
+	{
+		[Fact]
+		public void BoundsDefaultsConsistentForNewChildren() 
+		{
+			var layout = new AbsoluteLayout();
+
+			var child1 = new Label { }; // BindableObject
+			var child2 = NSubstitute.Substitute.For<IView>(); // Not a BindableObject
+
+			layout.Add(child1);
+			layout.Add(child2);
+
+			var bounds1 = layout.GetLayoutBounds(child1);
+			var bounds2 = layout.GetLayoutBounds(child2);
+
+			// The default layout bounds given to each of these child IViews _should_ be the same
+			Assert.Equal(bounds1.X, bounds2.X);
+			Assert.Equal(bounds1.Y, bounds2.Y);
+			Assert.Equal(bounds1.Width, bounds2.Width);
+			Assert.Equal(bounds1.Height, bounds2.Height);
+		}
+
+		[Fact]
+		public void BoundsDefaultsAttachedProperty()
+		{
+			var layout = new AbsoluteLayout();
+
+			var child = new Label { }; // BindableObject
+
+			layout.Add(child);
+
+			var bounds = layout.GetLayoutBounds(child);
+
+			Assert.Equal(0, bounds.X);
+			Assert.Equal(0, bounds.Y);
+			Assert.Equal(AbsoluteLayout.AutoSize, bounds.Width);
+			Assert.Equal(AbsoluteLayout.AutoSize, bounds.Height);
+		}
+
+		[Fact]
+		public void BoundsDefaultsRegularProperty()
+		{
+			var layout = new AbsoluteLayout();
+
+			var child = NSubstitute.Substitute.For<IView>(); // Not a BindableObject
+
+			layout.Add(child);
+
+			var bounds = layout.GetLayoutBounds(child);
+
+			Assert.Equal(0, bounds.X);
+			Assert.Equal(0, bounds.Y);
+			Assert.Equal(AbsoluteLayout.AutoSize, bounds.Width);
+			Assert.Equal(AbsoluteLayout.AutoSize, bounds.Height);
+		}
+	}
+}