added sealed

src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory.cs

@@ -9,7 +9,7 @@
 
 namespace Microsoft.CodeAnalysis.Semantics
 {
-    internal partial class CSharpOperationFactory
+    internal sealed partial class CSharpOperationFactory
     {
         private readonly ConcurrentDictionary<BoundNode, IOperation> _cache =
             new ConcurrentDictionary<BoundNode, IOperation>(concurrencyLevel: 2, capacity: 10);

src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory_Methods.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Collections.Immutable;
-using System.Linq;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 
 namespace Microsoft.CodeAnalysis.Semantics
 {
-    internal partial class CSharpOperationFactory
+    internal sealed partial class CSharpOperationFactory
     {
         private static Optional<object> ConvertToOptional(ConstantValue value)
         {

src/Compilers/VisualBasic/Portable/Operations/VisualBasicOperationFactory.vb

@@ -5,7 +5,7 @@ Imports System.Collections.Immutable
 Imports Microsoft.CodeAnalysis.VisualBasic
 
 Namespace Microsoft.CodeAnalysis.Semantics
-    Partial Friend Class VisualBasicOperationFactory
+    Partial Friend NotInheritable Class VisualBasicOperationFactory
 
         Private ReadOnly _cache As ConcurrentDictionary(Of BoundNode, IOperation) =
             New ConcurrentDictionary(Of BoundNode, IOperation)(concurrencyLevel:=2, capacity:=10)

src/Compilers/VisualBasic/Portable/Operations/VisualBasicOperationFactory_Methods.vb

 ' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 Imports System.Collections.Immutable
-Imports System.Runtime.CompilerServices
 Imports Microsoft.CodeAnalysis.VisualBasic
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.Semantics
-    Partial Friend Class VisualBasicOperationFactory
+    Partial Friend NotInheritable Class VisualBasicOperationFactory
         Private Shared Function ConvertToOptional(value As ConstantValue) As [Optional](Of Object)
             Return If(value Is Nothing, New [Optional](Of Object)(), New [Optional](Of Object)(value.Value))
         End Function
@@ -75,7 +74,7 @@ Namespace Microsoft.CodeAnalysis.Semantics
                 Case BoundKind.ByRefArgumentWithCopyBack
                     Dim byRefArgument = DirectCast(argument, BoundByRefArgumentWithCopyBack)
                     Dim parameter = parameters(index)
-                            Dim value = Create(byRefArgument.OriginalArgument)
+                    Dim value = Create(byRefArgument.OriginalArgument)
                     Return New Argument(
                         ArgumentKind.Explicit,
                         parameter,