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

tests/language/vm/if_conversion_vm_test.dart

Index: tests/language/vm/if_conversion_vm_test.dart
diff --git a/tests/language/vm/if_conversion_vm_test.dart b/tests/language/vm/if_conversion_vm_test.dart
index 2d97d4d4dfd0df968a5eb4967fe7ae4a359b938e..8fbcc3bccce4dc227ea5b721b53430a2e7cff5be 100644
--- a/tests/language/vm/if_conversion_vm_test.dart
+++ b/tests/language/vm/if_conversion_vm_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 // Test if-convertion pass in the optimizing compiler.
-// VMOptions=--optimization-counter-threshold=10 --no-use-osr
+// VMOptions=--optimization-counter-threshold=10 --no-use-osr --no-background-compilation
 
 import "package:expect/expect.dart";