Add test case for issue 7191.

tests/standalone/io/regress_7191_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.
+
+// Regression test for http://dartbug.com/7191.
+
+// Starts a sub-process which in turn starts another sub-process and then closes
+// its standard output. If handles are incorrectly inherited on Windows, this
+// will lead to a situation where the stdout of the first sub-process is never
+// closed which will make this test hang.
+
+import 'dart:io';
+
+main() {
+  var options = new Options();
+  var executable = options.executable;
+  var scriptDir = new Path.fromNative(options.script).directoryPath;
+  var script = scriptDir.append('regress_7191_script.dart').toNativePath();
+  Process.start(executable, [script]).then((process) {
+    process.stdin.write([0]);
+    process.stdout.onData = process.stdout.read;
+    process.stderr.onData = process.stderr.read;
+    process.stdout.onClosed = () {
+      process.stdin.write([0]);
+    };
+  });
+}