Add --no-background-compilation to tests that expect to run code in optimized form

tests/language/vm/optimized_check_class_test.dart

 // Copyright (c) 2015, 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
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr --no-background-compilation
 
 import "package:expect/expect.dart";
 
 // Test dense class-id checks. Regression test for issue 22104.
 
 class A {
   toString() => "an A";
 }
 
 class A1 extends A { }
@@ skipping 46 matching lines @@
     test_class_check(list[i]);
   }
   for (var i = 0; i < 100; i++) {
     Expect.equals("an A", test_class_check(new A1()));
   }
   Expect.equals("ha", test_class_check(new A4()));
 }