Use the right command for dartc.

tools/testing/dart/test_config_utils.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.
 
 #library("test_config_utils");
 
 /**
  * TestUtils is a collection of utility methods used to write
  * test_config.dart scripts for test suites.
  */
 class TestUtils {
 
   /**
    * Get a list of argument lists for the dart shell command.
    */
   static List<List<String>> argumentLists(String filename,
                                           Map optionsFromFile,
                                           Map configuration) {
     List args = ["--ignore-unrecognized-flags"];
     if (configuration["checked"]) {
       args.add("--enable_type_checks");
     }
     if (configuration["component"] == "leg") {
       args.add("--enable_leg");
     }
+    if (configuration["component"] == "dartc") {
+      if (configuration["mode"] == "release") {
+        args.add("--optimize");
+      }
+    }
 
     List<String> dartOptions = optionsFromFile["dartOptions"];
     args.addAll(dartOptions == null ? [filename] : dartOptions);
 
     var result = new List<List<String>>();
     List<List<String>> vmOptionsList = optionsFromFile["vmOptions"];
     if (vmOptionsList.isEmpty()) {
       result.add(args);
     } else {
       for (var vmOptions in vmOptionsList) {
@@ skipping 51 matching lines @@
     } else if (contents.contains("@dynamic-type-error") &&
                configuration['checked']) {
       isNegative = true;
     }
 
     return { "vmOptions": result,
              "dartOptions": dartOptions,
              "isNegative" : isNegative };
   }
 }