Change dart:io to use Future for one-shot operations.

tests/standalone/io/process_stdout_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.
 //
 // Process test program to test process communication.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
@@ skipping 39 matching lines @@
     input.onData = readData;
   };
 
   process.onExit = (exitCode) {
     Expect.equals(expectedExitCode, exitCode);
   };
 }
 
 main() {
   // Run the test using the process_test binary.
-  test(new Process.start(getProcessTestFileName(),
-                         const ["0", "1", "99", "0"]), 99);
+  test(Process.start(getProcessTestFileName(),
+                     const ["0", "1", "99", "0"]), 99);
 
   // Run the test using the dart binary with an echo script.
   // The test runner can be run from either the root or from runtime.
   var scriptFile = new File("tests/standalone/io/process_std_io_script.dart");
   if (!scriptFile.existsSync()) {
     scriptFile = new File("../tests/standalone/io/process_std_io_script.dart");
   }
   Expect.isTrue(scriptFile.existsSync());
-  test(new Process.start(new Options().executable, [scriptFile.name, "0"]), 0);
+  test(Process.start(new Options().executable, [scriptFile.name, "0"]), 0);
 }