Fix test failures. Ensure that BindingExtension is detected as such an not mistaken for the actual DataContext type.

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlCompiledBindingsMetadataRemover.cs

@@ -9,10 +9,10 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         public IXamlIlAstNode Transform(XamlIlAstTransformationContext context, IXamlIlAstNode node)
         {
             if (node is NestedScopeMetadataNode nestedScope)
-                return nestedScope.Value;
+                node = nestedScope.Value;
 
             if (node is AvaloniaXamlIlDataContextTypeMetadataNode dataContextType)
-                return dataContextType.Value;
+                node = dataContextType.Value;
 
             return node;
         }

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlDataContextTypeTransformer.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using Avalonia.Markup.Parsers;
@@ -143,7 +144,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         private static AvaloniaXamlIlDataContextTypeMetadataNode ParseDataContext(XamlIlAstTransformationContext context, XamlIlAstObjectNode on, XamlIlAstObjectNode obj)
         {
             var bindingType = context.GetAvaloniaTypes().IBinding;
-            if (!bindingType.IsAssignableFrom(obj.Type.GetClrType()))
+            if (!bindingType.IsAssignableFrom(obj.Type.GetClrType()) && !obj.Type.GetClrType().Equals(context.GetAvaloniaTypes().BindingExtension))
             {
                 return new AvaloniaXamlIlDataContextTypeMetadataNode(on, obj.Type.GetClrType());
             }
@@ -166,6 +167,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         }
     }
 
+    [DebuggerDisplay("DataType = {DataContextType}")]
     class AvaloniaXamlIlDataContextTypeMetadataNode : XamlIlValueWithSideEffectNodeBase
     {
         public virtual IXamlIlType DataContextType { get; }
@@ -177,6 +179,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         }
     }
 
+    [DebuggerDisplay("DataType = Unknown")]
     class AvaloniaXamlIlUninferrableDataContextMetadataNode : AvaloniaXamlIlDataContextTypeMetadataNode
     {
         public AvaloniaXamlIlUninferrableDataContextMetadataNode(IXamlIlAstValueNode value)

src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlWellKnownTypes.cs

@@ -37,6 +37,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         public IXamlIlType CompiledBindingExtension { get; }
         public IXamlIlType DataTemplate { get; }
         public IXamlIlType IItemsPresenterHost { get; }
+        public IXamlIlType BindingExtension { get; }
 
         public AvaloniaXamlIlWellKnownTypes(XamlIlTransformerConfiguration cfg)
         {
@@ -89,6 +90,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             CompiledBindingExtension = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindingExtension");
             DataTemplate = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.Templates.DataTemplate");
             IItemsPresenterHost = cfg.TypeSystem.GetType("Avalonia.Controls.Presenters.IItemsPresenterHost");
+            BindingExtension = cfg.TypeSystem.GetType("Avalonia.Markup.Xaml.MarkupExtensions.BindingExtension");
         }
     }