Fix #316

This change should hopefully end the MSBuild craziness that happens when
you add a file to the project using the VS Add Item dialog.

VS apparently has a behavior that intentionally tries to make sure the
added file is only included in a single itemgroup. So when Blazor
defines an itemgroup at the top level of scope with the same members as
Content - VS does some gymnastics to prevent it working.

The workaround is to defer the initialization of our itemgroup.

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

@@ -9,8 +9,5 @@
 
     <!-- When using IISExpress with a standalone app, there's no point restarting IISExpress after build. It slows things unnecessarily and breaks in-flight HTTP requests. -->
     <NoRestartServerOnBuild>true</NoRestartServerOnBuild>
-
-    <!-- We can remove this after updating to newer Razor tooling, where it's enabled by default -->
-    <UseRazorBuildServer>true</UseRazorBuildServer>
   </PropertyGroup>
 </Project>

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

@@ -5,20 +5,10 @@
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
   </PropertyGroup>
 
-  <!-- Temporary workaround for using the Razor Sdk targeted at preview2 Web.Sdk in a Preview environment -->
-  <ItemGroup Condition="'$(EnableDefaultItems)' == 'true' And '$(EnableDefaultContentItems)' == 'true'">
-    <!-- Both the preview1 Web.Sdk and preview2 Sdk include chstml files as content. Workaround this by removing and re-adding cshtml files -->
-    <Content Remove="**\*.cshtml" />
-
-    <Content Include="**\*.cshtml" CopyToPublishDirectory="PreserveNewest" Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder);$(DefaultWebContentItemExcludes)">
-      <Pack>$(IncludeRazorContentInPack)</Pack>
-    </Content>
-  </ItemGroup>
-
 
   <PropertyGroup>
     <!-- Passed to Razor tasks and loaded as a plugin -->
-      <_AngleSharpAssemblyPath>$(MSBuildThisFileDirectory)../tools/AngleSharp.dll</_AngleSharpAssemblyPath>
+    <_AngleSharpAssemblyPath>$(MSBuildThisFileDirectory)../tools/AngleSharp.dll</_AngleSharpAssemblyPath>
     <_BlazorExtensionAssemblyPath>$(MSBuildThisFileDirectory)../tools/Microsoft.AspNetCore.Blazor.Razor.Extensions.dll</_BlazorExtensionAssemblyPath>
 
     <!-- Deactivates the Razor SDK's build-time compilation. We do our own -->
@@ -37,7 +27,6 @@
 
   <!-- Something quick for input/output tracking - the assumptions here should match what the CLI does -->
   <ItemGroup>
-    <BlazorGenerate Include="**\*.cshtml" />
     <_BlazorGenerateDeclarationContent Include="@(Content->WithMetadataValue('Extension', '.cshtml'))" />
     <Content Update="@(_BlazorGenerateDeclarationContent)">
       <Generator>MSBuild:BlazorGenerateDeclaration</Generator>
@@ -77,6 +66,7 @@
   <PropertyGroup>
     <BlazorGenerateDeclarationDependsOn>
     _DefineBlazorPaths;
+    _ResolveBlazorInputs;
     _AssignBlazorGenerateTargetPaths;
     _HashBlazorGenerateInputs;
     </BlazorGenerateDeclarationDependsOn>
@@ -99,15 +89,20 @@
     </PropertyGroup>
   </Target>
 
+  <Target Name="_ResolveBlazorInputs">
+    <ItemGroup>
+      <BlazorGenerate Include="@(Content->WithMetadataValue('Extension', '.cshtml'))" />
+    </ItemGroup>
+  </Target>
+
   <!--
     Assigns each BlazorGenerate item a relative path based on where the directory structure. This accounts
     for <Link> and also for files outside of the project's folder hierarchy. So this is needed to support
     linked files.
 
     This step also assigns each item an output path for both stages of code generation.
   -->
-  <Target Name="_AssignBlazorGenerateTargetPaths">
-
+  <Target Name="_AssignBlazorGenerateTargetPaths"> 
     <AssignTargetPath Files="@(BlazorGenerate)" RootFolder="$(MSBuildProjectDirectory)">
       <Output TaskParameter="AssignedFiles" ItemName="BlazorGenerateWithTargetPath" />
     </AssignTargetPath>