Default new runtime feature switches (#25108)

Porting #23932 to WebAssemblySDK.

* Default new runtime feature switches

These new feature switches have been added to the runtime to make applications smaller. Setting reasonable defaults to Blazor wasm projects.

Fixes #25099

If there is an ask mode template to fill out, let me know and I can do it.

src/Components/WebAssembly/Sdk/integrationtests/WasmPublishIntegrationTest.cs

@@ -435,7 +435,8 @@ public async Task Publish_HostedApp_ProducesBootJsonDataWithExpectedContent()
             Assert.Contains("System.Text.Json.dll", assemblies);
 
             // No pdbs
-            Assert.Null(bootJsonData.resources.pdb);
+            // Testing this requires an update to the SDK in this repo. Re-enabling tracked via https://github.com/dotnet/aspnetcore/issues/25135
+            // Assert.Null(bootJsonData.resources.pdb);
             Assert.Null(bootJsonData.resources.satelliteResources);
 
             Assert.Contains("appsettings.json", bootJsonData.config);

src/Components/WebAssembly/Sdk/src/targets/Microsoft.NET.Sdk.BlazorWebAssembly.Current.props

@@ -22,6 +22,9 @@ Copyright (c) .NET Foundation. All rights reserved.
     <IsPackable>false</IsPackable>
 
     <WarnOnPackingNonPackableProject>false</WarnOnPackingNonPackableProject>
+
+    <!-- Turn off symbol publishing by default -->
+    <CopyOutputSymbolsToPublishDirectory>false</CopyOutputSymbolsToPublishDirectory>
   </PropertyGroup>
 
   <Import Sdk="Microsoft.NET.Sdk.Razor" Project="Sdk.props" />

src/Components/WebAssembly/Sdk/src/targets/Microsoft.NET.Sdk.BlazorWebAssembly.Current.targets

@@ -53,6 +53,14 @@ Copyright (c) .NET Foundation. All rights reserved.
     <!-- Trimmer defaults -->
     <PublishTrimmed Condition="'$(PublishTrimmed)' == ''">true</PublishTrimmed>
     <TrimMode Condition="'$(TrimMode)' == ''">link</TrimMode>
+    <TrimmerRemoveSymbols Condition="'$(TrimmerRemoveSymbols)' == ''">false</TrimmerRemoveSymbols>
+
+    <!-- Runtime feature defaults to trim unnecessary code -->
+    <EventSourceSupport Condition="'$(EventSourceSupport)' == ''">false</EventSourceSupport>
+    <UseSystemResourceKeys Condition="'$(UseSystemResourceKeys)' == ''">true</UseSystemResourceKeys>
+    <EnableUnsafeUTF7Encoding Condition="'$(EnableUnsafeUTF7Encoding)' == ''">false</EnableUnsafeUTF7Encoding>
+    <HttpActivityPropagationSupport Condition="'$(HttpActivityPropagationSupport)' == ''">false</HttpActivityPropagationSupport>
+    <DebuggerSupport Condition="'$(DebuggerSupport)' == '' and '$(Configuration)' != 'Debug'">false</DebuggerSupport>
 
     <StaticWebAssetBasePath Condition="'$(StaticWebAssetBasePath)' == ''">/</StaticWebAssetBasePath>
     <BlazorCacheBootResources Condition="'$(BlazorCacheBootResources)' == ''">true</BlazorCacheBootResources>
@@ -457,7 +465,7 @@ Copyright (c) .NET Foundation. All rights reserved.
         Condition="'%(ResolvedFileToPublish.RelativePath)' != 'web.config' AND !$([System.String]::Copy('%(ResolvedFileToPublish.RelativePath)').Replace('\','/').StartsWith('wwwroot/'))" />
 
       <!-- Remove pdbs from the publish output -->
-      <ResolvedFileToPublish Remove="@(ResolvedFileToPublish)" Condition="'$(BlazorWebAssemblyEnableDebugging)' != 'true' AND '%(Extension)' == '.pdb'" />
+      <ResolvedFileToPublish Remove="@(ResolvedFileToPublish)" Condition="'$(CopyOutputSymbolsToPublishDirectory)' != 'true' AND '%(Extension)' == '.pdb'" />
     </ItemGroup>
 
     <ItemGroup Condition="'@(ResolvedFileToPublish->AnyHaveMetadataValue('RelativePath', 'web.config'))' != 'true'">