Added comments regarding name scope task completions

src/Avalonia.Styling/Controls/INameScope.cs

@@ -20,6 +20,7 @@ namespace Avalonia.Controls
 
         /// <summary>
         /// Finds a named element in the name scope, waits for the scope to be completely populated before returning null
+        /// Returned task is configured to run any continuations synchronously.
         /// </summary>
         /// <param name="name">The name.</param>
         /// <returns>The element, or null if the name was not found.</returns>

src/Avalonia.Styling/Controls/NameScopeLocator.cs

@@ -49,6 +49,9 @@ namespace Avalonia.Controls
                 }
 
                 if (_task != null)
+                    // We expect everything to handle callbacks synchronously,
+                    // so the object graph is ready after its built
+                    // so keep TaskContinuationOptions.ExecuteSynchronously
                     _task.ContinueWith(t =>
                     {
                         observer.OnNext(t.Result);

tests/Avalonia.Controls.UnitTests/NameScopeTests.cs

@@ -51,6 +51,13 @@ namespace Avalonia.Controls.UnitTests
             Assert.Throws<InvalidOperationException>(() => target.Register("bar", element));
         }
 
+        
+        /*
+         `async void` here is intentional since we expect the continuation to be
+         executed *synchronously* and behave more like an event handler to make sure that
+         that the object graph is completely ready to use after it's built
+         rather than have pending continuations queued by SynchronizationContext.
+        */
         object _found = null;
         async void FindAsync(INameScope scope, string name)
         {