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

tests/language/deferred_optimized_test.dart

 // 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;
 
 import 'package:expect/expect.dart';
 
 bool libLoaded = false;
 
 main() {
   Expect.equals(88, heyhey());
@@ skipping 12 matching lines @@
 heyhey() => barbar();
 
 
 barbar() {
   if (libLoaded) {
     // Returns 42.
     return lib.foo();
   }
   return 88;
 }