In RazorCompiler, support HTML elements

samples/StandaloneApp/Home.cshtml

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

src/Microsoft.Blazor.Build/Core/RazorCompilation/Engine/BlazorIntermediateNodeWriter.cs

@@ -1,6 +1,9 @@
 // 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 AngleSharp;
+using AngleSharp.Html;
+using AngleSharp.Parser.Html;
 using Microsoft.AspNetCore.Razor.Language.CodeGeneration;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 using Microsoft.Blazor.RenderTree;
@@ -105,10 +108,44 @@ namespace Microsoft.Blazor.Build.Core.RazorCompilation.Engine
 
         public override void WriteHtmlContent(CodeRenderingContext context, HtmlContentIntermediateNode node)
         {
-            context.CodeWriter
-                .WriteStartMethodInvocation($"{builderVarName}.{nameof(RenderTreeBuilder.AddText)}")
-                .WriteStringLiteral(GetContent(node))
-                .WriteEndMethodInvocation();
+            var originalHtmlContent = GetContent(node);
+            var tokenizer = new HtmlTokenizer(
+                new TextSource(originalHtmlContent),
+                HtmlEntityService.Resolver);
+
+            HtmlToken nextToken;
+            while ((nextToken = tokenizer.Get()).Type != HtmlTokenType.EndOfFile)
+            {
+                switch (nextToken.Type)
+                {
+                    case HtmlTokenType.Character:
+                        // Text node
+                        context.CodeWriter
+                            .WriteStartMethodInvocation($"{builderVarName}.{nameof(RenderTreeBuilder.AddText)}")
+                            .WriteStringLiteral(nextToken.Data)
+                            .WriteEndMethodInvocation();
+                        break;
+
+                    case HtmlTokenType.StartTag:
+                        var nextTag = nextToken.AsTag();
+                        context.CodeWriter
+                            .WriteStartMethodInvocation($"{builderVarName}.{nameof(RenderTreeBuilder.OpenElement)}")
+                            .WriteStringLiteral(nextTag.Data)
+                            .WriteEndMethodInvocation();
+                        break;
+
+                    case HtmlTokenType.EndTag:
+                        context.CodeWriter
+                            .WriteStartMethodInvocation($"{builderVarName}.{nameof(RenderTreeBuilder.CloseElement)}")
+                            .WriteEndMethodInvocation();
+                        break;
+
+                    default:
+                        throw new InvalidCastException($"Unsupported token type: {nextToken.Type.ToString()}");
+                }
+            }
+
+            
         }
 
         public override void WriteUsingDirective(CodeRenderingContext context, UsingDirectiveIntermediateNode node)

test/Microsoft.Blazor.Build.Test/Microsoft.Blazor.Build.Test.csproj

@@ -7,7 +7,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="AngleSharp" Version="0.9.9.1" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="2.6.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
     <PackageReference Include="xunit" Version="2.3.1" />
@@ -22,4 +21,9 @@
     <Compile Include="..\shared\AssertNode.cs" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\anglesharp\AngleSharpBuilder\AngleSharpBuilder.csproj" ReferenceOutputAssembly="false" />
+    <Reference Include="AngleSharp" HintPath="..\..\src\anglesharp\AngleSharpBuilder\dist\AngleSharp.dll" />
+  </ItemGroup>
+
 </Project>

test/Microsoft.Blazor.Build.Test/RazorCompilerTest.cs

@@ -121,6 +121,19 @@ namespace Microsoft.Blazor.Build.Test
                 node => AssertNode.Text(node, "Third"));
         }
 
+        [Fact]
+        public void CanRenderElements()
+        {
+            // Arrange/Act
+            var component = CompileToComponent("<myelem>Hello</myelem>");
+
+            // Assert
+            var nodes = GetRenderTree(component).Where(NotWhitespace);
+            Assert.Collection(nodes,
+                node => AssertNode.Element(node, "myelem", 1),
+                node => AssertNode.Text(node, "Hello"));
+        }
+
         private static bool NotWhitespace(RenderTreeNode node)
             => node.NodeType != RenderTreeNodeType.Text
             || !string.IsNullOrWhiteSpace(node.TextContent);

test/Microsoft.Blazor.E2ETest/Tests/StandaloneAppTest.cs

@@ -27,10 +27,9 @@ namespace Microsoft.Blazor.E2ETest.Tests
         }
 
         [Fact]
-        public void HasBodyText()
+        public void HasHeading()
         {
-            var bodyText = Browser.FindElement(By.TagName("body")).Text;
-            Assert.Equal("Hello, world!", bodyText);
+            Assert.Equal("Hello, world!", Browser.FindElement(By.TagName("h1")).Text);
         }
 
         private void WaitUntilLoaded()