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

tests/language/mint_compares_test.dart

 // Copyright (c) 2012, 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
+// VMOptions=--optimization-counter-threshold=10 --no-background-compilation
 
 import "package:expect/expect.dart";
 
 // Test compares on 64-bit integers.
 
 compareTest() {
   Expect.isFalse(4294967296 < 6);
   Expect.isFalse(4294967296 < 4294967296);
   Expect.isFalse(4294967296 <= 6);
   Expect.isTrue(4294967296 <= 4294967296);
@@ skipping 75 matching lines @@
 bool gt2(a, b) => a > b ? true : false;
 bool gte2(a, b) => a >= b ? true : false;
 
 main() {
   for (var i = 0; i < 20; i++) {
     compareTest();
     compareTest2(lt1, lte1, gt1, gte1);
     compareTest2(lt2, lte2, gt2, gte2);
   }
 }