Stop spurious VS "cannot override ExecuteAsync" errors even if you don't specify a base class

src/Microsoft.Blazor/Components/RazorToolingWorkaround.cs

@@ -14,6 +14,7 @@
  */
 
 using System;
+using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Mvc
 {
@@ -23,7 +24,13 @@ namespace Microsoft.AspNetCore.Mvc
 
 namespace Microsoft.AspNetCore.Mvc.Razor
 {
-    public class RazorPage<T> { }
+    public class RazorPage<T> {
+
+        // This needs to be defined otherwise the VS tooling complains that there's no ExecuteAsync method to override.
+        public virtual Task ExecuteAsync()
+            => throw new NotImplementedException($"Blazor components do not implement {nameof(ExecuteAsync)}.");
+
+    }
 
     namespace Internal
     {