Use --use-cps-ir compiler option in the test script to run dart2js with the new backend.

tools/testing/dart/compiler_configuration.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.
 
 library compiler_configuration;
 
 import 'dart:io' show
     Platform;
 
 import 'runtime_configuration.dart' show
@@ skipping 235 matching lines @@
           isHostChecked: isHostChecked, useSdk: useSdk);
 
   int computeTimeoutMultiplier() {
     int multiplier = 1;
     if (isDebug) multiplier *= 4;
     if (isChecked) multiplier *= 2;
     if (isHostChecked) multiplier *= 16;
     return multiplier;
   }
 
-  Map<String, String> envWithCpsFlag(Map<String, String> env) {
-    if (env != environmentOverridesCacheObject || cpsFlagCache == null) {
-      cpsFlagCache = { 'DART_VM_OPTIONS' : '-DUSE_CPS_IR=true' };
-      if (env != null) {
-        cpsFlagCache.addAll(env);
-      }
-      environmentOverridesCacheObject = env;
-    }
-    return cpsFlagCache;
-  }
-
   CommandArtifact computeCompilationArtifact(
       String buildDir,
       String tempDir,
       CommandBuilder commandBuilder,
       List arguments,
       Map<String, String> environmentOverrides) {
-    var env = useCps ? envWithCpsFlag(environmentOverrides) :
-                       environmentOverrides;
+    List compilerArguments = new List.from(arguments)
+      ..addAll(extraDart2jsOptions);
     return new CommandArtifact(
         <Command>[
             this.computeCompilationCommand(
                 '$tempDir/out.js',
                 buildDir,
                 CommandBuilder.instance,
-                []..addAll(arguments)..addAll(extraDart2jsOptions),
-                env)],
+                compilerArguments,
+                environmentOverrides)],
         '$tempDir/out.js',
         'application/javascript');
   }
 
   List<String> computeRuntimeArguments(
       RuntimeConfiguration runtimeConfiguration,
       String buildDir,
       TestInformation info,
       List<String> vmOptions,
       List<String> sharedOptions,
@@ skipping 129 matching lines @@
       // shipped SDK, that is the script is not installed in
       // "$buildDir/dart-sdk/bin/"
       return '$prefix/dartanalyzer_developer$suffix';
     }
     if (useSdk) {
       prefix = '$buildDir/dart-sdk/bin';
     }
     return '$prefix/dartanalyzer$suffix';
   }
 }