dart:io | Add test of command-line arguments passed to main, remove test of Options object.

tests/standalone/io/arguments_test.dart

+// Copyright (c) 2013, 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.
+//
+// DartOptions=tests/standalone/io/arguments_test.dart 10 arguments_test 20
+
+import "package:expect/expect.dart";
+
+main(List<String> args) {
+  // Basic test for functionality.
+  Expect.equals(3, args.length);
+  Expect.equals(10, int.parse(args[0]));
+  Expect.equals("arguments_test", args[1]);
+  Expect.equals(20, int.parse(args[2]));
+  // Cannot add an additional argument.
+  Expect.throws(() => args.add("Fourth"), (e) => e is UnsupportedError);
+}