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

tests/language/named_parameters_with_conversions_test.dart

 // Copyright (c) 2011, 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.
 //
 // Test named arguments work as expected regardless of whether the function or
 // method is called via function call syntax or method call syntax.
-// VMOptions=--optimization-counter-threshold=10
+// VMOptions=--optimization-counter-threshold=10 --no-background-compilation
 
 import "package:expect/expect.dart";
 
 
 Validate(tag, a, b) {
   // tag encodes which parameters are passed in with values a: 111, b: 222.
   if (tag == 'ab') {
     Expect.equals(a, 111);
     Expect.equals(b, 222);
   }
@@ skipping 119 matching lines @@
     testMethodCallSyntax(new HasField());
     testFunctionCallSyntax(new HasMethod());
   }
 }
 
 main() {
   for (var i = 0; i < 20; i++) {
     NamedParametersWithConversionsTest.testMain();
   }
 }