Remove BoundConversion.OriginalUserDefinedConversionsOpt property

src/Compilers/CSharp/Portable/BoundTree/BoundExpression.cs

@@ -477,7 +477,7 @@ public override bool SuppressVirtualCalls
 
         public BoundConversion UpdateOperand(BoundExpression operand)
         {
-            return this.Update(operand: operand, this.Conversion, this.IsBaseConversion, this.Checked, this.ExplicitCastInCode, this.ConstantValueOpt, this.ConversionGroupOpt, this.OriginalUserDefinedConversionsOpt, this.Type);
+            return this.Update(operand: operand, this.Conversion, this.IsBaseConversion, this.Checked, this.ExplicitCastInCode, this.ConstantValueOpt, this.ConversionGroupOpt, this.Type);
         }
 
         /// <summary>

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

@@ -902,10 +902,6 @@
          Conversion is represented by a single BoundConversion.
          -->
     <Field Name="ConversionGroupOpt" Type="ConversionGroup?"/>
-    <!--The set of method symbols from which this conversion's method was chosen.
-        Only kept in the tree if the conversion was an error and overload resolution
-        was unable to choose a best method.-->
-    <Field Name="OriginalUserDefinedConversionsOpt" Type="ImmutableArray&lt;MethodSymbol&gt;" Null="Allow" SkipInNullabilityRewriter="true"/>
   </Node>
 
   <!--

src/Compilers/CSharp/Portable/BoundTree/Constructors.cs

@@ -336,7 +336,6 @@ public static BoundConversion SynthesizedNonUserDefined(SyntaxNode syntax, Bound
                 explicitCastInCode: false,
                 conversionGroupOpt: null,
                 constantValueOpt: constantValueOpt,
-                originalUserDefinedConversionsOpt: default,
                 type: type)
             { WasCompilerGenerated = true };
         }
@@ -391,35 +390,9 @@ public BoundConversion(
                 explicitCastInCode: explicitCastInCode,
                 constantValueOpt: constantValueOpt,
                 conversionGroupOpt,
-                conversion.OriginalUserDefinedConversions,
                 type: type,
                 hasErrors: hasErrors || !conversion.IsValid)
         { }
-
-        public BoundConversion(
-            SyntaxNode syntax,
-            BoundExpression operand,
-            Conversion conversion,
-            bool isBaseConversion,
-            bool @checked,
-            bool explicitCastInCode,
-            ConstantValue? constantValueOpt,
-            ConversionGroup? conversionGroupOpt,
-            TypeSymbol type,
-            bool hasErrors = false) :
-            this(syntax, operand, conversion, isBaseConversion, @checked, explicitCastInCode, constantValueOpt, conversionGroupOpt, originalUserDefinedConversionsOpt: default, type, hasErrors)
-        {
-        }
-
-        public BoundConversion Update(BoundExpression operand,
-                                      Conversion conversion,
-                                      bool isBaseConversion,
-                                      bool @checked,
-                                      bool explicitCastInCode,
-                                      ConstantValue? constantValueOpt,
-                                      ConversionGroup? conversionGroupOpt,
-                                      TypeSymbol type)
-            => Update(operand, conversion, isBaseConversion, @checked, explicitCastInCode, constantValueOpt, conversionGroupOpt, this.OriginalUserDefinedConversionsOpt, type);
     }
 
     internal sealed partial class BoundBinaryOperator

src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs

@@ -3534,7 +3534,7 @@ boundNode.ExpressionSymbol is Symbol accessSymbol &&
                         }
                         else if (conversion.ConversionKind.IsUserDefinedConversion())
                         {
-                            GetSymbolsAndResultKind(conversion, conversion.SymbolOpt, conversion.OriginalUserDefinedConversionsOpt, out symbols, out resultKind);
+                            GetSymbolsAndResultKind(conversion, conversion.SymbolOpt, conversion.Conversion.OriginalUserDefinedConversions, out symbols, out resultKind);
                         }
                         else
                         {