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

tests/language/vm/regress_23117_vm_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.
 // Test location summary for Uint32 multiplication.
-// VMOptions=--optimization-counter-threshold=5
+// VMOptions=--optimization-counter-threshold=5 --no-background-compilation
 
 import 'package:expect/expect.dart';
 
 mintLeftShift(x, y) => x << y;
 mintRightShift(x, y) => x >> y;
 
 main() {
   for (var i = 0; i < 20; i++) {
     var x = 1 + (1 << (i + 32));
     Expect.equals(x, mintLeftShift(x, 0));
     Expect.equals(x, mintRightShift(x, 0));
     Expect.equals(2*x, mintLeftShift(x, 1));
     Expect.equals(x~/2, mintRightShift(x, 1));
     Expect.equals(x, mintRightShift(mintLeftShift(x, i), i));
   }
 }