Replace run_selenium.py with Dart script that uses the browser controller for performance tests.

tools/testing/dart/http_server.dart

 // Copyright (c) 2013, 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 http_server;
 
 import 'dart:async';
 import 'dart:io';
 import 'test_suite.dart';  // For TestUtils.
 // TODO(efortuna): Rewrite to not use the args library and simply take an
@@ skipping 83 matching lines @@
     "/favicon.ico",
     "/foo",
     "/bar",
     "/NonExistingFile",
     "/NonExistingFile.js",
     "/hahaURL",
   ];
 
   List _serverList = [];
   Path _buildDirectory = null;
+  Path _dartDirectory = null;
   final bool useContentSecurityPolicy;
   final String runtime;
 
   TestingServers(Path buildDirectory,
                  this.useContentSecurityPolicy,
-                 [String this.runtime = 'none']) {
+                 [String this.runtime = 'none', String dartDirectory]) {
     _buildDirectory = TestUtils.absolutePath(buildDirectory);
+    _dartDirectory = dartDirectory == null ? TestUtils.dartDir()
+        : new Path(dartDirectory);
   }
 
   int get port => _serverList[0].port;
   int get crossOriginPort => _serverList[1].port;
 
   /**
    * [startServers] will start two Http servers.
    * The first server listens on [port] and sets
    *   "Access-Control-Allow-Origin: *"
    * The second server listens on [crossOriginPort] and sets
@@ skipping 110 matching lines @@
     var requestPath = new Path(urlRequestPath.substring(1)).canonicalize();
     var pathSegments = requestPath.segments();
     if (pathSegments.length > 0) {
       var basePath;
       var relativePath;
       if (pathSegments[0] == PREFIX_BUILDDIR) {
         basePath = _buildDirectory;
         relativePath = new Path(
             pathSegments.skip(1).join('/'));
       } else if (pathSegments[0] == PREFIX_DARTDIR) {
-        basePath = TestUtils.dartDir();
+        basePath = _dartDirectory;
         relativePath = new Path(
             pathSegments.skip(1).join('/'));
       }
       var packagesDirName = 'packages';
       var packagesIndex = pathSegments.indexOf(packagesDirName);
       if (packagesIndex != -1) {
         var start = packagesIndex + 1;
         basePath = _buildDirectory.append(packagesDirName);
         relativePath = new Path(pathSegments.skip(start).join('/'));
       }
@@ skipping 135 matching lines @@
 class _Entry {
   final String name;
   final String displayName;
 
   _Entry(this.name, this.displayName);
 
   int compareTo(_Entry other) {
     return name.compareTo(other.name);
   }
 }