Add support for --dart2js-path and --dart2js-args.

lib/src/runner/browser/platform.dart

 // Copyright (c) 2016, 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 96 matching lines @@
   final _compileFutures = new Map<String, Future>();
 
   /// Mappers for Dartifying stack traces, indexed by test path.
   final _mappers = new Map<String, StackTraceMapper>();
 
   BrowserPlatform._(this._server, Configuration config, {String root})
       : _root = root == null ? p.current : root,
         _config = config,
         _compiledDir = config.pubServeUrl == null ? createTempDir() : null,
         _http = config.pubServeUrl == null ? null : new HttpClient(),
-        _compilers = new CompilerPool(color: config.color) {
+        _compilers = new CompilerPool(config) {
     var cascade = new shelf.Cascade()
         .add(_webSocketHandler.handler);
 
     if (_config.pubServeUrl == null) {
       cascade = cascade
           .add(_createPackagesHandler())
           .add(_jsHandler.handler)
           .add(createStaticHandler(_root))
           .add(_wrapperHandler);
     }
@@ skipping 295 matching lines @@
     await Future.wait(futures);
 
     if (_config.pubServeUrl == null) {
       new Directory(_compiledDir).deleteSync(recursive: true);
     } else {
       _http.close();
     }
   });
   final _closeMemo = new AsyncMemoizer();
 }