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

tests/lib/typed_data/float32x4_unbox_phi_test.dart

Index: tests/lib/typed_data/float32x4_unbox_phi_test.dart
diff --git a/tests/lib/typed_data/float32x4_unbox_phi_test.dart b/tests/lib/typed_data/float32x4_unbox_phi_test.dart
index 9309642988934841617dd5fe478aec0ac5da92f2..c44ae5e4dc2fbfe69c6921ae4571cc9ce8a1f390 100644
--- a/tests/lib/typed_data/float32x4_unbox_phi_test.dart
+++ b/tests/lib/typed_data/float32x4_unbox_phi_test.dart
@@ -1,7 +1,7 @@
 // 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=--deoptimization_counter_threshold=1000 --optimization-counter-threshold=10
+// VMOptions=--deoptimization_counter_threshold=1000 --optimization-counter-threshold=10 --no-background-compilation
 
 // Library tag to be able to run in html test framework.
 library float32x4_unbox_regress_test;