Alternative approach binding IntoVariable inspired by @AnthonyDGreen …

…`CaseType` prototype.

** Note need test cases adding_ **

src/Compilers/VisualBasic/Portable/BoundTree/BoundNodes.xml

@@ -552,7 +552,8 @@
 
     <Node Name="BoundExpressionIntoVariable" Base="BoundExpression">
       <Field Name="Expression" Type="BoundExpression" />
-      <Field Name="Variable" Type="BoundExpression" />
+      <Field Name="Variable" Type="LocalSymbol" />
+      <Field Name="ConditionOpt" Type="BoundExpression" Null="allow" />
     </Node>
 
     <AbstractNode Name="BoundStatement" Base="BoundNode"/>

src/Compilers/VisualBasic/Portable/BoundTree/Expression.vb

@@ -224,7 +224,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
     Partial Friend Class BoundExpressionIntoVariable
         Protected Overrides ReadOnly Property Children As ImmutableArray(Of BoundNode)
             Get
-                Return ImmutableArray.Create(Of BoundNode)(Me.Expression, Me.Variable)
+                Return ImmutableArray.Create(Of BoundNode)(Me.Expression)
             End Get
         End Property
     End Class

src/Compilers/VisualBasic/Portable/Errors/Errors.vb

@@ -2037,5 +2037,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         FEATURE_CommentsAfterLineContinuation
         FEATURE_TypeOfMany
         FEATURE_IntoVariable
+        ERR_UnnecessaryNullableType
+        ERR_NoConversion
     End Enum
 End Namespace