In RazorCompiler, allow HTML comments

samples/StandaloneApp/App.cshtml

@@ -1,2 +1,8 @@
 @using Microsoft.AspNetCore.Blazor.Browser.Routing
-<c:BrowserRouter AppAssembly=@(typeof(StandaloneApp.Program).Assembly) PagesNamespace=@("StandaloneApp.Pages") />
+<!--
+    Configuring this stuff here is temporary. Later we'll move the app config
+    into Program.cs, and it won't be necessary to specify AppAssembly.
+-->
+<c:BrowserRouter
+    AppAssembly=@(typeof(StandaloneApp.Program).Assembly)
+    PagesNamespace=@("StandaloneApp.Pages") />

src/Microsoft.AspNetCore.Blazor.Razor.Extensions/BlazorIntermediateNodeWriter.cs

@@ -285,6 +285,9 @@ namespace Microsoft.AspNetCore.Blazor.Razor
                             break;
                         }
 
+                    case HtmlTokenType.Comment:
+                        break;
+
                     default:
                         throw new InvalidCastException($"Unsupported token type: {nextToken.Type.ToString()}");
                 }

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

@@ -187,6 +187,19 @@ namespace Microsoft.AspNetCore.Blazor.Build.Test
                 frame => AssertFrame.Element(frame, "img", 1, 1));
         }
 
+        [Fact]
+        public void SupportsComments()
+        {
+            // Arrange/Act
+            var component = CompileToComponent("Start<!-- My comment -->End");
+            var frames = GetRenderTree(component);
+
+            // Assert
+            Assert.Collection(frames,
+                frame => AssertFrame.Text(frame, "Start", 0),
+                frame => AssertFrame.Text(frame, "End", 1));
+        }
+
         [Fact]
         public void SupportsAttributesWithLiteralValues()
         {