Remove unusued variables.

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

@@ -286,7 +286,6 @@ Namespace Microsoft.CodeAnalysis.Semantics
         End Function
 
         Private Function CreateBoundMeReferenceOperation(boundMeReference As BoundMeReference) As IInstanceReferenceExpression
-            Dim isBaseReference = False
             Dim syntax As SyntaxNode = boundMeReference.Syntax
             Dim type As ITypeSymbol = boundMeReference.Type
             Dim constantValue As [Optional](Of Object) = ConvertToOptional(boundMeReference.ConstantValueOpt)
@@ -295,7 +294,6 @@ Namespace Microsoft.CodeAnalysis.Semantics
         End Function
 
         Private Function CreateBoundMyBaseReferenceOperation(boundMyBaseReference As BoundMyBaseReference) As IInstanceReferenceExpression
-            Dim isBaseReference = True
             Dim syntax As SyntaxNode = boundMyBaseReference.Syntax
             Dim type As ITypeSymbol = boundMyBaseReference.Type
             Dim constantValue As [Optional](Of Object) = ConvertToOptional(boundMyBaseReference.ConstantValueOpt)
@@ -304,7 +302,6 @@ Namespace Microsoft.CodeAnalysis.Semantics
         End Function
 
         Private Function CreateBoundMyClassReferenceOperation(boundMyClassReference As BoundMyClassReference) As IInstanceReferenceExpression
-            Dim isBaseReference = True
             Dim syntax As SyntaxNode = boundMyClassReference.Syntax
             Dim type As ITypeSymbol = boundMyClassReference.Type
             Dim constantValue As [Optional](Of Object) = ConvertToOptional(boundMyClassReference.ConstantValueOpt)