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

tests/standalone/io/process_check_arguments_test.dart

Index: tests/standalone/io/process_check_arguments_test.dart
diff --git a/tests/standalone/io/process_check_arguments_test.dart b/tests/standalone/io/process_check_arguments_test.dart
index 4f1c0a676df5cbaf334dfe27e7dc966976fd3e54..a5ce40c86363f772942e60b1bb50a69d97cd7c4a 100644
--- a/tests/standalone/io/process_check_arguments_test.dart
+++ b/tests/standalone/io/process_check_arguments_test.dart
@@ -6,7 +6,7 @@
 #source("process_test_util.dart");
 
 test(args) {
-  Process process = new Process.start(getDartFileName(), args);
+  Process process = new Process.start(new Options().executable, args);
   // Wait for the process to exit and then check result.
   process.onExit = (exitCode) {
     Expect.equals(0, exitCode);