Fix #14144 confusing error message misusing a callable object

tests/language/vm/no_such_method_error_message_vm_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // VMOptions=--optimization-counter-threshold=10 --no-use-osr --no-background-compilation
 
 import "package:expect/expect.dart";
 
 // Test error message with noSuchMethodError: non-existent names
 // should result in a message that reports the missing method.
 
 call_bar(x) => x.bar();
 
 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();
 }
-