Fix #14144 confusing error message misusing a callable object

tests/language/vm/no_such_method_error_message_vm_test.dart

Index: tests/language/vm/no_such_method_error_message_vm_test.dart
diff --git a/tests/language/vm/no_such_method_error_message_vm_test.dart b/tests/language/vm/no_such_method_error_message_vm_test.dart
index 259a13a045fabe4a445570df023933c5aeb841bb..575a9662e54049630ce52854cacfb2f7f5da602c 100644
--- a/tests/language/vm/no_such_method_error_message_vm_test.dart
+++ b/tests/language/vm/no_such_method_error_message_vm_test.dart
@@ -14,12 +14,10 @@ testMessage() {
   try {
     call_bar(5);
   } catch (e) {
-    Expect.isTrue(e.toString().indexOf("has no instance method 'bar'") != -1);
+    Expect.isTrue(e.toString().contains("has no instance method 'bar'"));
   }
 }
 
-
 main() {
   for (var i = 0; i < 20; i++) testMessage();
 }
-