fix: Revert "Keep track of current view type even if content is set t…

…o null"

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_NativeFrame.cs

@@ -1,4 +1,4 @@
-
+#if __ANDROID__
 #pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
 
 using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -12,14 +12,12 @@
 using Windows.UI.Xaml;
 using System.Threading.Tasks;
 using System.Diagnostics;
-using Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls.FramePages;
 
 namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls
 {
 	[TestClass]
 	public class Given_NativeFrame
 	{
-#if __ANDROID__
 		[TestMethod]
 		[RunsOnUIThread]
 		public async Task When_NavigateForward()
@@ -71,48 +69,10 @@ async Task WaitForPages(int count)
 
 			await WaitForPages(1);
 		}
-#endif
-		[TestMethod]
-		[RunsOnUIThread]
-		public async Task When_ContentIsNullAndNavigate()
-		{
-#if !NETFX_CORE
-			var style = Windows.UI.Xaml.Application.Current.Resources["NativeDefaultFrame"] as Style;
-			Assert.IsNotNull(style);
-
-			var SUT = new Frame()
-			{
-				Style = style
-			};
-#else
-			var SUT = new Frame();
-#endif
-
-			TestServices.WindowHelper.WindowContent = SUT;
-
-			SUT.Navigate(typeof(FirstPage));
-
-			var firstPage = SUT.Content as FirstPage;
-
-			Assert.IsNotNull(firstPage.FirstTextBlock);
-			Assert.AreEqual("Page The First", firstPage.FirstTextBlock.Text);
-
-			SUT.Content = null;
-			SUT.BackStack?.Clear();
-
-
-			SUT.Navigate(typeof(SecondPage));
-			var secondPage = SUT.Content as SecondPage;
-
-			Assert.IsNotNull(SUT.BackStack.FirstOrDefault());
-			Assert.AreEqual(typeof(FirstPage), SUT.BackStack.FirstOrDefault().SourcePageType);
-
-			Assert.IsNotNull(secondPage.SecondTextBlock);
-			Assert.AreEqual("Page The Second", secondPage.SecondTextBlock.Text);
-		}
 	}
 
 	partial class MyPage : Page
 	{
 	}
 }
+#endif

src/Uno.UI.RuntimeTests/Uno.UI.RuntimeTests.csproj

@@ -99,16 +99,6 @@
 		</ProjectReference>
 	</ItemGroup>
 
-	<ItemGroup>
-	  <None Remove="Tests\Windows_UI_Xaml_Controls\FramePages\FirstPage.xaml" />
-	  <None Remove="Tests\Windows_UI_Xaml_Controls\FramePages\SecondPage.xaml" />
-	</ItemGroup>
-
-	<ItemGroup>
-	  <UpToDateCheckInput Remove="Tests\Windows_UI_Xaml_Controls\FramePages\FirstPage.xaml" />
-	  <UpToDateCheckInput Remove="Tests\Windows_UI_Xaml_Controls\FramePages\SecondPage.xaml" />
-	</ItemGroup>
-
 	<ItemGroup>
 	  <Compile Include="Tests\Windows_UI_Xaml_Controls\HtmlElementAttributeTests\Given_HtmlElementAttribute.Wasm.cs" />
 	</ItemGroup>

src/Uno.UI/UI/Xaml/Controls/Frame/Frame.cs

@@ -43,6 +43,17 @@ public Frame()
 
 		internal PageStackEntry CurrentEntry { get; set; }
 
+		protected override void OnContentChanged(object oldValue, object newValue)
+		{
+			base.OnContentChanged(oldValue, newValue);
+
+			// Make sure we void CurrentEntry when someone sets Frame.Content = null;
+			if (newValue == null)
+			{
+				CurrentEntry = null;
+			}
+		}
+
 		#region BackStackDepth DependencyProperty
 
 		public int BackStackDepth