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

tests/language/div_with_power_of_two_test.dart

Index: tests/language/div_with_power_of_two_test.dart
diff --git a/tests/language/div_with_power_of_two_test.dart b/tests/language/div_with_power_of_two_test.dart
index a6285634517b15935d17f31802355d29f9db2f7e..fd88c4c3034f4d46b3a6067336c7cbba8014df88 100644
--- a/tests/language/div_with_power_of_two_test.dart
+++ b/tests/language/div_with_power_of_two_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 // Test division by power of two.
 // Test that results before and after optimization are the same.
-// VMOptions=--optimization-counter-threshold=10 --no-use-osr
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr --no-background-compilation
 
 import "package:expect/expect.dart";