Fix newly added regression test that left processes hanging on Windows.

tests/standalone/io/regress_7191_script.dart

Index: tests/standalone/io/regress_7191_script.dart
diff --git a/tests/standalone/io/regress_7191_script.dart b/tests/standalone/io/regress_7191_script.dart
index 9ba5e607a479fa0378b05b267a39e679e368a217..d90f0b544c29283b5bdd2e9bfcfe98e354707d41 100644
--- a/tests/standalone/io/regress_7191_script.dart
+++ b/tests/standalone/io/regress_7191_script.dart
@@ -18,13 +18,13 @@ main() {
       // When receiving data again, kill sub-process and exit.
       stdin.onData = () {
         var data = stdin.read();
-        Expect.listEquals([1], data);
+        Expect.listEquals([0], data);
         p.kill();
-        p.onExit = port.close;
+        p.onExit = exit;
       };
       // Close stdout. If handles are incorrectly inherited this will
       // not actually close stdout and the test will hang.
       stdout.close();
     });
   };
-}
+}