Load performance CSS samples from disk instead of URLs

Replace URL-based stylesheet loading with local CSS files to eliminate
network dependency. Several original URLs were dead or returning HTML
error pages. The 8 valid CSS files are now committed under Samples/ and
loaded via the new FileTests class. Also fix PlatformNotSupportedException
from RuntimeHelpers.PrepareMethod on .NET 10.

Author: jafin

src/AngleSharp.Performance.Css/AngleSharp.Performance.Css.csproj

@@ -1,16 +1,22 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ApplicationIcon />
     <OutputType>Exe</OutputType>
     <StartupObject />
     <AutoGenerateBindingRedirects>false</AutoGenerateBindingRedirects>
-    <LangVersion>9</LangVersion>
+    <LangVersion>default</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Debug|netstandard2.0|AnyCPU'">
     <PlatformTarget>AnyCPU</PlatformTarget>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Content Include="Samples\*.css">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\AngleSharp.Performance.Common\AngleSharp.Performance.Common.csproj" />
     <ProjectReference Include="..\AngleSharp.Performance.Utilities\AngleSharp.Performance.Utilities.csproj" />

src/AngleSharp.Performance.Css/Program.cs

@@ -2,29 +2,15 @@ namespace AngleSharp.Performance.Css
 {
     using System;
     using System.Collections.Generic;
+    using System.IO;
 
     class Program
     {
         static void Main(String[] args)
         {
-            var stylesheets = new UrlTests(
-                extension: ".css", 
-                withBuffer: true);
-
-            stylesheets.Include(
-                "http://www.csszengarden.com/215/215.css?v=8may2013",
-                "http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css",
-                "http://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.11.4/jquery-ui.css",
-                "http://www.florian-rappl.de/Content/style?v=o2O40dFmfq2JG0tQyfQctozyaA9IcUQxq9b6x16JOKw1",
-                "http://z-ecx.images-amazon.com/images/G/01/AUIClients/AmazonUI-a607978b4c59f6c52279818077903ce9a01d14e2.rendering_engine-not-trident.min._V2_.css",
-                "http://assets-cdn.github.com/assets/github2/index-0d569068eabc0305b93b246950eb913fc9d2948b952824895172164835b351dd.css",
-                "http://codeproject.cachefly.net/App_Themes/CodeProject/Css/Main.min.css?dt=2.8.150616.1",
-                "http://cdn.sstatic.net/stackoverflow/all.css?v=5a386bc7d85d",
-                "http://fbstatic-a.akamaihd.net/rsrc.php/v2/yX/r/fr81HMP3WaY.css",
-                "https://s.yimg.com/zz/combo?/os/stencil/3.1.0/styles-ltr.css&/os/fp/atomic-css.2c9008c2.css",
-                "http://static.licdn.com/sc/h/59ugqor0mlj9qjt7ohmi1kpko,cy00fqioblh011agl8l3n36sc",
-                "http://style.aliunicorn.com/css/6v/??apollo/core/core-ws-responsive.css,run/wholesale/font-v1.css,run/site/en/common/header/header-v150213.css,run/site/en/common/bottombar/bottom-bar.css?t=145f12b3e_104c763f9a",
-                "http://www.florian-rappl.de/Content/style?v=o2O40dFmfq2JG0tQyfQctozyaA9IcUQxq9b6x16JOKw1").Wait();
+            var samplesDir = Path.Combine(AppContext.BaseDirectory, "Samples");
+            var stylesheets = new FileTests()
+                .IncludeFromDirectory(samplesDir);
 
             var parsers = new List<ITestee>
             {