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

tests/language/megamorphic_no_such_method_test.dart

Index: tests/language/megamorphic_no_such_method_test.dart
diff --git a/tests/language/megamorphic_no_such_method_test.dart b/tests/language/megamorphic_no_such_method_test.dart
index 92e082670faba5e56d32706a0500df771dd756f7..603fba4880999ea10586a7062668bd6af3695307 100644
--- a/tests/language/megamorphic_no_such_method_test.dart
+++ b/tests/language/megamorphic_no_such_method_test.dart
@@ -2,7 +2,7 @@
 // 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.
 // Test program for correct optimizations related to types fo allocated lists.
-// VMOptions=--optimization-counter-threshold=10 --no-use-osr
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr --no-background-compilation
 
 import "package:expect/expect.dart";