don't search for legacy typevars in newtypes

Author: oconnor663

crates/ty_python_semantic/src/types.rs

@@ -7215,13 +7215,10 @@ impl<'db> Type<'db> {
                 instance.find_legacy_typevars_impl(db, binding_context, typevars, visitor);
             }
 
-            Type::NewTypeInstance(newtype) => {
-                newtype.base_class_type(db).find_legacy_typevars_impl(
-                    db,
-                    binding_context,
-                    typevars,
-                    visitor,
-                );
+            Type::NewTypeInstance(_) => {
+                // A newtype can never be constructed from an unspecialized generic class, so it is
+                // impossible that we could ever find any legacy typevars in a newtype instance or
+                // its underlying class.
             }
 
             Type::SubclassOf(subclass_of) => {