Fix listening for multiple signals.

tests/standalone/io/signal_test_script.dart

 // Copyright (c) 2014, 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.
 
 import "dart:io";
 import "dart:async";
 
 void main(args) {
-  var signal;
   // This process should die if it never receives a signal.
   var timeout = new Timer(new Duration(seconds: 25), () => exit(1));
-  switch (args[0]) {
-    case 'SIGHUP': signal = ProcessSignal.SIGHUP; break;
-    case 'SIGINT': signal = ProcessSignal.SIGINT; break;
-    case 'SIGTERM': signal = ProcessSignal.SIGTERM; break;
-    case 'SIGUSR1': signal = ProcessSignal.SIGUSR1; break;
-    case 'SIGUSR2': signal = ProcessSignal.SIGUSR2; break;
-    case 'SIGWINCH': signal = ProcessSignal.SIGWINCH; break;
+  for (var arg in args) {
+    var signal;
+    switch (arg) {
+      case 'SIGHUP': signal = ProcessSignal.SIGHUP; break;
+      case 'SIGINT': signal = ProcessSignal.SIGINT; break;
+      case 'SIGTERM': signal = ProcessSignal.SIGTERM; break;
+      case 'SIGUSR1': signal = ProcessSignal.SIGUSR1; break;
+      case 'SIGUSR2': signal = ProcessSignal.SIGUSR2; break;
+      case 'SIGWINCH': signal = ProcessSignal.SIGWINCH; break;
+    }
+    signal.watch().first.then((s) {
+      if (signal != s) exit(1);
+      if (signal.toString() != arg) exit(1);
+      print(signal);
+      exit(0);
+    });
   }
-  signal.watch().first.then((s) {
-    if (signal != s) exit(1);
-    if (signal.toString() != args[0]) exit(1);
-    print('got signal');
-    timeout.cancel();
-  });
   print("ready");
 }