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

tests/language/deferred_optimized_test.dart

Index: tests/language/deferred_optimized_test.dart
diff --git a/tests/language/deferred_optimized_test.dart b/tests/language/deferred_optimized_test.dart
index ef3c2a0cde54b10604bdd6f3f9480d3fabeea800..bb62884007b9b2f0738fd498c87aeafa414fc498 100644
--- a/tests/language/deferred_optimized_test.dart
+++ b/tests/language/deferred_optimized_test.dart
@@ -1,7 +1,7 @@
 // Copyright (c) 2014, 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-inlining
+// VMOptions=--optimization-counter-threshold=10 --no-use-inlining --no-background-compilation
 
 // Declares foo that returns 42.
 import "deferred_constraints_lib2.dart" deferred as lib;