Correctly handle the --arch argument to dart test scripts.

tests/stub-generator/test_config.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("stub_generator_test_config");
 
 #import("../../tools/testing/dart/test_suite.dart");
 
 class StubGeneratorTestSuite extends StandardTestSuite {
   String dartcPath;
@@ skipping 63 matching lines @@
   void generateTestCase(String filename,
                         String interfaceFile,
                         String classes,
                         Function onGenerated) {
     testGeneratorStarted();
     Directory temp = new Directory('');
     temp.createTempSync();
     File stubsOutFile = new File("${temp.path}/${interfaceFile}");
     stubsOutFile.createSync();
     String stubsPath = stubsOutFile.fullPathSync();
-    Process dartcProcess = new Process(dartcPath,
-                                       [filename,
-                                        '-noincremental',
-                                        '-out', temp.path,
-                                        '-isolate-stub-out', stubsPath,
-                                        '-generate-isolate-stubs', classes ]);
+    List<String> args = [filename,
+                         '-noincremental',
+                         '-out', temp.path,
+                         '-isolate-stub-out', stubsPath,
+                         '-generate-isolate-stubs', classes ];
+    if (configuration['verbose']) {
+      print("# $dartcPath ${Strings.join(args, ' ')}");
+    }
+    Process dartcProcess = new Process(dartcPath, args);
     dartcProcess.exitHandler = (int exitCode) {
       combineFiles(filename, stubsPath, onGenerated);
     };
     dartcProcess.start();
   }
 
   void processFile(String filename) {
     // Only run the tests that match the pattern.
     RegExp pattern = configuration['selectors'][suiteName];
     if (!pattern.hasMatch(filename)) return;
@@ skipping 13 matching lines @@
         String interfaceFile = splitIsolateStubsOptions[0];
         String classes = splitIsolateStubsOptions[1];
         generateTestCase(filename, interfaceFile, classes, (String filename) {
           createTestCase(filename, optionsFromFile['isNegative']);
           testGeneratorDone();
         });
       }
     }
   }
 }