Add firefox support.

lib/src/runner/loader.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.loader;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
@@ skipping 100 matching lines @@
 
     return Future.wait(_platforms.map((platform) {
       return new Future.sync(() {
         if (!metadata.testOn.evaluate(platform, os: currentOS)) return null;
 
         if (_pubServeUrl != null && !p.isWithin('test', path)) {
           throw new LoadException(path,
               'When using "pub serve", all test files must be in test/.');
         }
 
-        if (platform == TestPlatform.chrome) return _loadBrowserFile(path);
+        if (platform.isBrowser) return _loadBrowserFile(path, platform);
         assert(platform == TestPlatform.vm);
         return _loadVmFile(path);
       }).then((suite) {
         if (suite == null) return null;
         return suite.change(metadata: metadata).filter(platform, os: currentOS);
       });
     })).then((suites) => suites.where((suite) => suite != null).toList());
   }
 
   /// Load the test suite at [path] in a browser.
-  Future<Suite> _loadBrowserFile(String path) =>
-      _browserServer.then((browserServer) => browserServer.loadSuite(path));
+  Future<Suite> _loadBrowserFile(String path, TestPlatform platform) =>
+      _browserServer.then((browserServer) =>
+          browserServer.loadSuite(path, platform));
 
   /// Load the test suite at [path] in VM isolate.
   Future<Suite> _loadVmFile(String path) {
     var packageRoot = packageRootFor(path, _packageRoot);
     var receivePort = new ReceivePort();
 
     return new Future.sync(() {
       if (_pubServeUrl != null) {
         var url = _pubServeUrl.resolve(
             p.withoutExtension(p.relative(path, from: 'test')) +
@@ skipping 57 matching lines @@
   Future close() {
     for (var isolate in _isolates) {
       isolate.kill();
     }
     _isolates.clear();
 
     if (_browserServerCompleter == null) return new Future.value();
     return _browserServer.then((browserServer) => browserServer.close());
   }
 }