Add a command line option to use the new CPS based backend.

tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart

Index: tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart
diff --git a/tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart b/tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart
index 9ea920102e7e3325ecc4c135f1e0f732ec398dc7..163e58d89f9f6f2775e9bdcdd5d4d60c017d6dee 100644
--- a/tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart
+++ b/tests/compiler/dart2js/js_backend_cps_ir_source_information_test.dart
@@ -1,7 +1,6 @@
 // Copyright (c) 2015, 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=-DUSE_CPS_IR=true
 
 // Test that the CPS IR code generator generates source information.
 
@@ -68,13 +67,10 @@ String getCodeForMethod(Compiler compiler, String name) {
 }
 
 runTests(List<TestEntry> tests) {
-  Expect.isTrue(const bool.fromEnvironment("USE_CPS_IR"),
-      'Run with USE_CPS_IR=true');
-
   for (TestEntry test in tests) {
     Map files = {TEST_MAIN_FILE: test.source};
     asyncTest(() {
-      Compiler compiler = compilerFor(files);
+      Compiler compiler = compilerFor(files, options: <String>['--use-cps-ir']);
       Uri uri = Uri.parse('memory:$TEST_MAIN_FILE');
       return compiler.run(uri).then((bool success) {
         Expect.isTrue(success);
@@ -133,7 +129,7 @@ const List<TestEntry> tests = const [
 main() { print('Hello World'); }
 """, const ['memory:test.dart:[1,10]']),
 const TestEntry("""
-main() { 
+main() {
   print('Hello');
   print('World');
 }