On RenderTreeBuilder, add SetUpdatesAttributeName (#11375)

Author: SteveSandersonMS

src/Components/Components/ref/Microsoft.AspNetCore.Components.netstandard2.0.cs

@@ -775,6 +775,7 @@ public void OpenComponent(int sequence, System.Type componentType) { }
         public void OpenComponent<TComponent>(int sequence) where TComponent : Microsoft.AspNetCore.Components.IComponent { }
         public void OpenElement(int sequence, string elementName) { }
         public void SetKey(object value) { }
+        public void SetUpdatesAttributeName(string updatesAttributeName) { }
     }
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
     public readonly partial struct RenderTreeDiff

src/Components/Components/src/RenderTree/RenderTreeBuilder.cs

@@ -516,6 +516,24 @@ public void AddMultipleAttributes<T>(int sequence, IEnumerable<KeyValuePair<stri
             }
         }
 
+        /// <summary>
+        /// <para>
+        /// Indicates that the preceding attribute represents an event handler
+        /// whose execution updates the attribute with name <paramref name="updatesAttributeName"/>.
+        /// </para>
+        /// <para>
+        /// This information is used by the rendering system to determine whether
+        /// to accept a value update for the other attribute when receiving a
+        /// call to the event handler.
+        /// </para>
+        /// </summary>
+        /// <param name="updatesAttributeName">The name of another attribute whose value can be updated when the event handler is executed.</param>
+        public void SetUpdatesAttributeName(string updatesAttributeName)
+        {
+            // TODO: This will be implemented in a later PR, once aspnetcore-tooling
+            // is updated to call this method.
+        }
+
         /// <summary>
         /// Appends a frame representing a child component.
         /// </summary>