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

tests/language/smi_type_test.dart

 // Copyright (c) 2013, 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=8
+// VMOptions=--optimization-counter-threshold=8 --no-background-compilation
 
 import "package:expect/expect.dart";
 
 main() {
   // Make instance-of polymorphic.
   isNum([]);
   isNumRaw([]);
   isNotNum([]);
   isNotInt([]);
   for (int i = 0; i < 20; i++) {
@@ skipping 12 matching lines @@
   return a is Comparable;
 }
 
 isNotNum(a) {
   return a is Comparable<String>;
 }
 
 isNotInt(a) {
   return a is Comparable<double>;
 }