Eagerly close browser tests.

test/runner/signal_test.dart

 // Copyright (c) 2015, 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.
 
 // Windows doesn't support sending signals.
 @TestOn("vm && !windows")
 
 import 'dart:async';
 import 'dart:io';
 
@@ skipping 234 matching lines @@
       var test = _runTest(["test.dart"]);
       test.stdout.expect(consumeThrough("running test"));
       signalAndQuit(test);
 
       d.file("output", "true").validate();
       expectTempDirEmpty();
     });
   });
 }
 
-ScheduledProcess _runTest(List<String> args) =>
-    runTest(args, environment: {"_UNITTEST_TEMP_DIR": _tempDir});
+ScheduledProcess _runTest(List<String> args, {bool forwardStdio: false}) =>
+    runTest(args,
+        environment: {"_UNITTEST_TEMP_DIR": _tempDir},
+        forwardStdio: forwardStdio);
 
 void signalAndQuit(ScheduledProcess test) {
   test.signal(ProcessSignal.SIGTERM);
   test.shouldExit();
   test.stderr.expect(isDone);
 }
 
 void expectTempDirEmpty() {
   schedule(() => expect(new Directory(_tempDir).listSync(), isEmpty));
 }