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

tests/standalone/io/process_run_output_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.
 //
 // Test script for testing that output is handled correctly for
 // non-interactive processes started with Process.run.
 
 #import("dart:io");
 #source("process_test_util.dart");
 
@@ skipping 13 matching lines @@
     enc = Encoding.ASCII;
   } else if (encoding == 'latin1') {
     enc = Encoding.ISO_8859_1;
   } else if (encoding == 'utf8') {
     enc = Encoding.UTF_8;
   }
 
   var options = new ProcessOptions();
   if (stream == 'stdout') {
     options.stdoutEncoding = enc;
-    new Process.run(new Options().executable, [scriptFile, encoding, stream],
-                    options, (exit, out, err) {
-      Expect.equals(exit, 0);
-      Expect.equals(err, '');
-      checkOutput(encoding, out);
+    Process.run(new Options().executable,
+                [scriptFile, encoding, stream],
+                options). then((result) {
+      Expect.equals(result.exitCode, 0);
+      Expect.equals(result.stderr, '');
+      checkOutput(encoding, result.stdout);
     });
   } else {
     options.stderrEncoding = enc;
-    new Process.run(new Options().executable, [scriptFile, encoding, stream],
-                    options, (exit, out, err) {
-      Expect.equals(exit, 0);
-      Expect.equals(out, '');
-      checkOutput(encoding, err);
+    Process.run(new Options().executable,
+                [scriptFile, encoding, stream],
+                options).then((result) {
+      Expect.equals(result.exitCode, 0);
+      Expect.equals(result.stdout, '');
+      checkOutput(encoding, result.stderr);
     });
   }
 }
 
 main() {
   var scriptFile = new File("tests/standalone/io/process_std_io_script2.dart");
   if (!scriptFile.existsSync()) {
     scriptFile =
         new File("../tests/standalone/io/process_std_io_script2.dart");
   }
   Expect.isTrue(scriptFile.existsSync());
   test(scriptFile.name, 'ascii', 'stdout');
   test(scriptFile.name, 'ascii', 'stderr');
   test(scriptFile.name, 'latin1', 'stdout');
   test(scriptFile.name, 'latin1', 'stderr');
   test(scriptFile.name, 'utf8', 'stdout');
   test(scriptFile.name, 'utf8', 'stderr');
 
 }