Add LayoutDisplay component and use it in StandaloneApp

samples/StandaloneApp/App.cshtml

@@ -0,0 +1,2 @@
+@using Microsoft.AspNetCore.Blazor.Layouts
+<c:LayoutDisplay Page=@typeof(StandaloneApp.Pages.Home) />

samples/StandaloneApp/Home.cshtml

@@ -1 +0,0 @@
-<h1>Hello, world!</h1>

samples/StandaloneApp/Pages/Home.cshtml

@@ -0,0 +1,2 @@
+@(Layout<StandaloneApp.Shared.MainLayout>())
+<h1>Hello, world!</h1>

samples/StandaloneApp/Program.cs

@@ -9,7 +9,7 @@ namespace StandaloneApp
     {
         public static void Main(string[] args)
         {
-            new BrowserRenderer().AddComponent<Home>("app");
+            new BrowserRenderer().AddComponent<App>("app");
         }
     }
 }

samples/StandaloneApp/Shared/MainLayout.cshtml

@@ -0,0 +1,11 @@
+@using Microsoft.AspNetCore.Blazor.RenderTree
+@(Implements<Microsoft.AspNetCore.Blazor.Layouts.ILayoutComponent>())
+
+<fieldset>
+    <legend>Layout</legend>
+    @Body
+</fieldset>
+
+@functions {
+    public RenderFragment Body { get; set; }
+}

src/Microsoft.AspNetCore.Blazor.Build/targets/All.targets

@@ -1,6 +1,9 @@
 <Project>
   <PropertyGroup>
     <BlazorBuildExe>dotnet &quot;$(MSBuildThisFileDirectory)../tools/Microsoft.AspNetCore.Blazor.Build.dll&quot;</BlazorBuildExe>
+  
+    <!-- The Blazor build code can only find your referenced assemblies if they are in the output directory -->
+    <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
   </PropertyGroup>
 
   <Import Project="RazorCompilation.targets" />

src/Microsoft.AspNetCore.Blazor/Layouts/LayoutDisplay.cs

@@ -0,0 +1,67 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Reflection;
+using Microsoft.AspNetCore.Blazor.Components;
+using Microsoft.AspNetCore.Blazor.RenderTree;
+
+namespace Microsoft.AspNetCore.Blazor.Layouts
+{
+    /// <summary>
+    /// Displays the specified page component, rendering it inside its layout
+    /// and any further nested layouts.
+    /// </summary>
+    public class LayoutDisplay : IComponent
+    {
+        private RenderHandle _renderHandle;
+        
+        /// <summary>
+        /// Gets or sets the type of the page component to display.
+        /// The type must implement <see cref="IComponent"/>.
+        /// </summary>
+        public Type Page { get; set; }
+
+        /// <inheritdoc />
+        public void Init(RenderHandle renderHandle)
+        {
+            _renderHandle = renderHandle;
+        }
+
+        /// <inheritdoc />
+        public void SetParameters(ParameterCollection parameters)
+        {
+            parameters.AssignToProperties(this);
+            Render();
+        }
+
+        private void Render()
+        {
+            // In the middle, we render the requested page
+            var fragment = RenderComponentWithBody(Page, bodyParam: null);
+
+            // Repeatedly wrap it in each layer of nested layout until we get
+            // to a layout that has no parent
+            Type layoutType = Page;
+            while ((layoutType = GetLayoutType(layoutType)) != null)
+            {
+                fragment = RenderComponentWithBody(layoutType, fragment);
+            }
+            
+            _renderHandle.Render(fragment);
+        }
+
+        private RenderFragment RenderComponentWithBody(Type componentType, RenderFragment bodyParam) => builder =>
+        {
+            builder.OpenComponent(0, componentType);
+            if (bodyParam != null)
+            {
+                builder.AddAttribute(1, nameof(ILayoutComponent.Body), bodyParam);
+            }
+            builder.CloseComponent();
+        };
+
+        private Type GetLayoutType(Type type)
+            => type.GetCustomAttribute<LayoutAttribute>()?.LayoutType;
+    }
+}