Skip BoundQueryClause nodes in visitors.

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

@@ -1846,14 +1846,14 @@
     <!-- The query variable introduced by this query clause, if any. -->
     <Field Name="DefinedSymbol" Type="RangeVariableSymbol?"/>
     <!-- The bound expression that invokes the operation of the query clause. -->
-    <Field Name="Operation" Type="BoundExpression?" />
+    <Field Name="Operation" Type="BoundExpression?" SkipInVisitor="true"/>
     <!-- The bound expression that is the invocation of a "Cast" method specified by the query translation. -->
-    <Field Name="Cast" Type="BoundExpression?" />
+    <Field Name="Cast" Type="BoundExpression?" SkipInVisitor="true"/>
     <!-- The enclosing binder in which the query clause was evaluated. -->
     <Field Name="Binder" Type="Binder" Null="disallow" />
     <!-- The bound expression that is the query expression in "unoptimized" form.  Specifically, a final ".Select"
          invocation that is omitted by the specification is included here. -->
-    <Field Name="UnoptimizedForm" Type="BoundExpression?" />
+    <Field Name="UnoptimizedForm" Type="BoundExpression?" SkipInVisitor="true"/>
   </Node>
 
   <!-- 

src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs

@@ -8778,9 +8778,6 @@ internal abstract partial class BoundTreeWalker: BoundTreeVisitor
         public override BoundNode? VisitQueryClause(BoundQueryClause node)
         {
             this.Visit(node.Value);
-            this.Visit(node.Operation);
-            this.Visit(node.Cast);
-            this.Visit(node.UnoptimizedForm);
             return null;
         }
         public override BoundNode? VisitTypeOrInstanceInitializers(BoundTypeOrInstanceInitializers node)
@@ -9838,9 +9835,9 @@ internal abstract partial class BoundTreeRewriter : BoundTreeVisitor
         public override BoundNode? VisitQueryClause(BoundQueryClause node)
         {
             BoundExpression value = (BoundExpression)this.Visit(node.Value);
-            BoundExpression? operation = (BoundExpression?)this.Visit(node.Operation);
-            BoundExpression? cast = (BoundExpression?)this.Visit(node.Cast);
-            BoundExpression? unoptimizedForm = (BoundExpression?)this.Visit(node.UnoptimizedForm);
+            BoundExpression? operation = node.Operation;
+            BoundExpression? cast = node.Cast;
+            BoundExpression? unoptimizedForm = node.UnoptimizedForm;
             TypeSymbol type = this.VisitType(node.Type);
             return node.Update(value, node.DefinedSymbol, operation, cast, node.Binder, unoptimizedForm, type);
         }
@@ -11597,9 +11594,9 @@ public NullabilityRewriter(ImmutableDictionary<BoundExpression, (NullabilityInfo
         public override BoundNode? VisitQueryClause(BoundQueryClause node)
         {
             BoundExpression value = (BoundExpression)this.Visit(node.Value);
-            BoundExpression? operation = (BoundExpression?)this.Visit(node.Operation);
-            BoundExpression? cast = (BoundExpression?)this.Visit(node.Cast);
-            BoundExpression? unoptimizedForm = (BoundExpression?)this.Visit(node.UnoptimizedForm);
+            BoundExpression? operation = node.Operation;
+            BoundExpression? cast = node.Cast;
+            BoundExpression? unoptimizedForm = node.UnoptimizedForm;
             BoundQueryClause updatedNode;
 
             if (_updatedNullabilities.TryGetValue(node, out (NullabilityInfo Info, TypeSymbol Type) infoAndType))