Always suppress references expressed only in *.nuspec files

- needed even in servicing builds

Author: dougbu

eng/targets/ResolveReferences.targets

@@ -157,7 +157,11 @@
       <UnusedBaselinePackageReference Include="@(BaselinePackageReference)"
           Exclude="@(Reference);@(_ProjectReferenceByAssemblyName);@(PackageReference)" />
 
-      <!-- Only allow suppressing baseline changes in non-servicing builds. -->
+      <!-- Handle suppressions needed because above Exclude is not aware of references added in .nuspec files. -->
+      <UnusedBaselinePackageReference Remove="@(SuppressBaselineReference->WithMetadataValue('InNuspecFile', 'true'))"
+          Condition=" '$(IsServicingBuild)' == 'true' " />
+
+      <!-- Allow suppressions of any baseline changes in non-servicing builds. -->
       <UnusedBaselinePackageReference Remove="@(SuppressBaselineReference)"
           Condition=" '$(IsServicingBuild)' != 'true' " />
 

src/Components/Components/src/Microsoft.AspNetCore.Components.csproj

@@ -22,12 +22,19 @@
     <Reference Include="System.Buffers" />
   </ItemGroup>
 
-  <!-- These references were removed in 3.0 -->
+  <!--
+    These references exist only in the .nuspec files and baseline checks are not aware of them. Keep suppressions
+    in sync with the two .nuspec files:
+    - Anytime a reference is added to this project file, remove its suppression.
+    - Remove InNuspecFile attributes of references removed from the .nuspec files. Make suppression conditional on
+      Major.Minor during previews. After RTM (and baseline updates), remove suppressions entirely.
+  -->
   <ItemGroup>
-    <SuppressBaselineReference Include="Microsoft.AspNetCore.Components.Analyzers" />
-    <SuppressBaselineReference Include="Microsoft.AspNetCore.Authorization" />
-    <SuppressBaselineReference Include="Microsoft.JSInterop" />
-    <SuppressBaselineReference Include="System.ComponentModel.Annotations" />
+    <SuppressBaselineReference Include="Microsoft.AspNetCore.Components.Analyzers" InNuspecFile="true" />
+    <SuppressBaselineReference Include="Microsoft.AspNetCore.Authorization" InNuspecFile="true" />
+    <SuppressBaselineReference Include="Microsoft.JSInterop" InNuspecFile="true" />
+    <SuppressBaselineReference Include="System.ComponentModel.Annotations" InNuspecFile="true"
+        Condition=" '$(TargetFramework)'=='netstandard2.0' " />
   </ItemGroup>
 
   <Target Name="_GetNuspecDependencyPackageVersions">