Add executable to Options interface to get the name of the executable used to execute the script.

tests/standalone/io/test_runner_test.dart

 // Copyright (c) 2012, 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.
 
 #import("dart:io");
 #import("../../../tools/testing/dart/test_runner.dart");
 #import("../../../tools/testing/dart/status_file_parser.dart");
 #import("../../../tools/testing/dart/test_options.dart");
 #source("process_test_util.dart");
 
@@ skipping 27 matching lines @@
 
 TestCase MakeTestCase(String testName, List<String> expectations) {
   String test_path = "tests/standalone/${testName}.dart";
   // Working directory may be dart/runtime rather than dart.
   if (!new File(test_path).existsSync()) {
     test_path = "../tests/standalone/${testName}.dart";
   }
 
   var configuration = new TestOptionsParser().parse(['--timeout', '2'])[0];
   return new TestCase(testName,
-                      [new Command(getDartFileName(),
+                      [new Command(new Options().executable,
                                    <String>["--ignore-unrecognized-flags",
                                             "--enable_type_checks",
                                             test_path])],
                       configuration,
                       TestController.processCompletedTest,
                       new Set<String>.from(expectations));
 }
 
 
 void main() {
   new RunningProcess(MakeTestCase("pass_test", [PASS])).start();
   new RunningProcess(MakeTestCase("fail_test", [FAIL])).start();
   new RunningProcess(MakeTestCase("timeout_test", [TIMEOUT])).start();
 
   // The crash test sometimes times out.  Run it with a large timeout to help
   // diagnose the delay.
   // The test loads a new executable, which may sometimes take a long time.
   // It involves a wait on the VM event loop, and possible system delays.
   var configuration = new TestOptionsParser().parse(['--timeout', '60'])[0];
   new RunningProcess(new TestCase("CrashTest",
                                   [new Command(getProcessTestFileName(),
                                                const ["0", "0", "1", "1"])],
                                   configuration,
                                   TestController.processCompletedTest,
                                   new Set<String>.from([CRASH]))).start();
   Expect.equals(4, TestController.numTests);
   // Throw must be from body of start() function for this test to work.
   Expect.throws(new RunningProcess(MakeTestCase("pass_test", [SKIP])).start);
 }