Fix a bug with Control+C and browsers.

lib/src/runner/browser/server.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.
 
 library test.runner.browser.server;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 413 matching lines @@
     var hostUrl = (_pubServeUrl == null ? url : _pubServeUrl)
         .resolve('packages/test/src/runner/browser/static/index.html');
 
     var browser = _newBrowser(hostUrl.replace(queryParameters: {
       'managerUrl': webSocketUrl.toString()
     }), platform);
     _browsers[platform] = browser;
 
     // TODO(nweiz): Gracefully handle the browser being killed before the
     // tests complete.
-    browser.onExit.catchError((error, stackTrace) {
+    browser.onExit.then((_) {
+      if (completer.isCompleted) return;
+      if (!_closed) return;
+      completer.complete(null);
+    }).catchError((error, stackTrace) {
       if (completer.isCompleted) return;
       completer.completeError(error, stackTrace);
     });
 
     return completer.future.timeout(new Duration(seconds: 7), onTimeout: () {
       throw new ApplicationException(
           "Timed out waiting for ${platform.name} to connect.");
     });
   }
 
@@ skipping 11 matching lines @@
         throw new ArgumentError("$browser is not a browser.");
     }
   }
 
   /// Closes the server and releases all its resources.
   ///
   /// Returns a [Future] that completes once the server is closed and its
   /// resources have been fully released.
   Future close() {
     return _closeThunk.run(() async {
-      var futures = _browserManagers.keys.map((platform) async {
-        await _browserManagers[platform];
-        await _browsers[platform].close();
-      }).toList();
+      var futures = _browsers.values.map((browser) => browser.close()).toList();
 
       futures.add(_server.close());
       futures.add(_compilers.close());
 
       await Future.wait(futures);
 
       if (_pubServeUrl == null) {
         new Directory(_compiledDir).deleteSync(recursive: true);
       } else {
         _http.close();
       }
     });
   }
 }