Add Microsoft.Build.Tasks.Core to ApiCompat

runApiCompat.bat

@@ -9,6 +9,6 @@ RoboCopy "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFr
 RoboCopy "C:\Program Files (x86)\Reference Assemblies\Microsoft\MSBuild\v14.0" "%MSBUILD_ROOT%ref"
 
 REM Run ApiCompat
-\\fxcore\tools\bin\ApiCompat.exe "%MSBUILD_ROOT%\bin\Windows_NT\Debug-NetCore\Microsoft.Build.Framework.dll,%MSBUILD_ROOT%\bin\Windows_NT\Debug-NetCore\Microsoft.Build.Utilities.Core.dll" -implDirs:"%MSBUILD_ROOT%ref" -contractDepends:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6,C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6\Facades" -out:Differences.txt -baseline:CompatBaseline.txt
+\\fxcore\tools\bin\ApiCompat.exe "%MSBUILD_ROOT%\bin\Windows_NT\Debug-NetCore\Microsoft.Build.Framework.dll,%MSBUILD_ROOT%\bin\Windows_NT\Debug-NetCore\Microsoft.Build.Utilities.Core.dll,%MSBUILD_ROOT%\bin\Windows_NT\Debug-NetCore\Microsoft.Build.Tasks.Core.dll" -implDirs:"%MSBUILD_ROOT%ref" -contractDepends:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6,C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6\Facades" -out:Differences.txt -baseline:CompatBaseline.txt
 
-endlocal
+endlocal

src/Shared/Compat/SerializableAttribute.cs

@@ -4,14 +4,14 @@ namespace System
 {
     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Delegate, Inherited = false)]
     [ComVisible(true)]
-    public sealed class SerializableAttribute : Attribute
+    internal sealed class SerializableAttribute : Attribute
     {
         public SerializableAttribute() { }
     }
 
     [AttributeUsage(AttributeTargets.Field, Inherited = false)]
     [ComVisible(true)]
-    public sealed class NonSerializedAttribute : Attribute
+    internal sealed class NonSerializedAttribute : Attribute
     {
         public NonSerializedAttribute() { }
     }

src/XMakeCommandLine/MSBuild.csproj

@@ -51,6 +51,9 @@
     <Compile Include="..\Shared\Compat\SafeHandleZeroOrMinusOneIsInvalid.cs">
       <Link>Compat\SafeHandleZeroOrMinusOneIsInvalid.cs</Link>
     </Compile>
+    <Compile Include="..\Shared\Compat\SerializableAttribute.cs">
+      <Link>Compat\SerializableAttribute.cs</Link>
+    </Compile>
     <Compile Include="..\Shared\FxCopExclusions\Microsoft.Build.Shared.Suppressions.cs">
       <ExcludeFromStyleCop>true</ExcludeFromStyleCop>
     </Compile>