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

tests/language/try_catch_optimized4_test.dart

 // Copyright (c) 2014, 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 correct dead phi elimination with try catch.
 
 List<Object> a = [1,2,3,4,5];
 
 class MyError { }
 
 class M {
@@ skipping 17 matching lines @@
     }
   }
 }
 
 main() {
   for (var i = 0; i < 20; i++) loop_test();
 }