Eagerly close browser tests.

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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:async/async.dart';
 import 'package:http_multi_server/http_multi_server.dart';
@@ skipping 367 matching lines @@
     // Capture errors and release them later to avoid Zone issues. This call to
     // [_browserManagerFor] is running in a different [LoadSuite] than future
     // calls, which means they're also running in different error zones so
     // errors can't be freely passed between them. Storing the error or value as
     // an explicit [Result] fixes that.
     _browserManagers[platform] = Result.capture(future);
 
     return future;
   }
 
+  /// Close all the browsers that the server currently has open.
+  ///
+  /// Note that this doesn't close the server itself. Browser tests can still be
+  /// loaded, they'll just spawn new browsers.
+  Future closeBrowsers() {
+    var managers = _browserManagers.values.toList();
+    _browserManagers.clear();
+    return Future.wait(managers.map((manager) async {
+      var result = await manager;
+      if (result.isError) return;
+      await result.asValue.value.close();
+    }));
+  }
+
   /// 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 _closeMemo.runOnce(() async {
       var futures = _browserManagers.values.map((future) async {
         var result = await future;
         if (result.isError) return;
 
         await result.asValue.value.close();
       }).toList();
 
       futures.add(_server.close());
       futures.add(_compilers.close());
 
       await Future.wait(futures);
 
       if (_config.pubServeUrl == null) {
         new Directory(_compiledDir).deleteSync(recursive: true);
       } else {
         _http.close();
       }
     });
   }
 }