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

tests/standalone/io/process_test_util.dart

Index: tests/standalone/io/process_test_util.dart
diff --git a/tests/standalone/io/process_test_util.dart b/tests/standalone/io/process_test_util.dart
index 1de73cb037cd2c69ab416ada04ee5f9a1535454d..61ad729b8240d3207d9c31d6a2f749acf0cad7ae 100644
--- a/tests/standalone/io/process_test_util.dart
+++ b/tests/standalone/io/process_test_util.dart
@@ -2,13 +2,6 @@
 // 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.
 
-String getPlatformOutDir() {
-  var os = Platform.operatingSystem;
-  if (os == 'linux') return 'out/';
-  if (os == 'macos') return 'xcodebuild/';
-  return '';  // Windows.
-}
-
 String getPlatformExecutableExtension() {
   var os = Platform.operatingSystem;
   if (os == 'windows') return '.exe';
@@ -16,37 +9,10 @@ String getPlatformExecutableExtension() {
 }
 
 String getProcessTestFileName() {
-  var outDir = getPlatformOutDir();
-  var extension = getPlatformExecutableExtension();
-  // We do not expose information about the mode or architecture we are testing
-  // to the tests themselves, so we use any working copy.
-  var names = ['${outDir}Release_ia32/process_test$extension',
-               '${outDir}Debug_ia32/process_test$extension',
-               '${outDir}Release_x64/process_test$extension',
-               '${outDir}Debug_x64/process_test$extension'];
-
-  for (var name in names) {
-    if (new File(name).existsSync()) {
-      return name;
-    }
-  }
-  Expect.fail('Could not find the process_test executable.');
-}
-
-String getDartFileName() {
-  var outDir = getPlatformOutDir();
   var extension = getPlatformExecutableExtension();
-  // We do not expose information about the mode or architecture we are testing
-  // to the tests themselves, so we use any working dart shell.
-  var names = ['${outDir}Release_ia32/dart$extension',
-               '${outDir}Debug_ia32/dart$extension',
-               '${outDir}Release_x64/dart$extension',
-               '${outDir}Debug_x64/dart$extension'];
-
-  for (var name in names) {
-    if (new File(name).existsSync()) {
-      return name;
-    }
-  }
-  Expect.fail('Could not find the dart executable.');
+  var executable = new Options().executable;
+  var dirIndex = executable.lastIndexOf('dart$extension');
+  var buffer = new StringBuffer(executable.substring(0, dirIndex));
+  buffer.add('process_test$extension');
+  return buffer.toString();
 }