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

tools/testing/dart/browser_controller.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 browser;
 
 import "dart:async";
 import "dart:convert" show LineSplitter, UTF8;
 import "dart:core";
 import "dart:io";
 
@@ skipping 742 matching lines @@
 
   var adbDeviceMapping = new Map<String, AdbDevice>();
   // This cache is used to guarantee that we never see double reporting.
   // If we do we need to provide developers with this information.
   // We don't add urls to the cache until we have run it.
   Map<int, String> testCache = new Map<int, String>();
   Map<int, String> doubleReportingOutputs = new Map<int, String>();
 
   BrowserTestingServer testingServer;
 
+  /**
+   * The TestRunner takes the testingServer in as a constructor parameter in
+   * case we wish to have a testing server with different behavior (such as the
+   * case for performance testing.
+   */
   BrowserTestRunner(this.globalConfiguration,
                     this.localIp,
                     this.browserName,
                     this.maxNumBrowsers,
-                    {bool this.checkedMode: false});
+                    {bool this.checkedMode: false,
+                    BrowserTestingServer this.testingServer});
 
   Future<bool> start() {
     // If [browserName] doesn't support opening new windows, we use new iframes
     // instead.
     bool useIframe =
         !Browser.BROWSERS_WITH_WINDOW_SUPPORT.contains(browserName);
-    testingServer = new BrowserTestingServer(
-        globalConfiguration, localIp, useIframe);
+    if (testingServer == null) {
+      testingServer = new BrowserTestingServer(
+          globalConfiguration, localIp, useIframe);
+    }
     return testingServer.start().then((_) {
       testingServer.testDoneCallBack = handleResults;
       testingServer.testStatusUpdateCallBack = handleStatusUpdate;
       testingServer.testStartedCallBack = handleStarted;
       testingServer.nextTestCallBack = getNextTest;
       return getBrowsers().then((browsers) {
         var futures = [];
         for (var browser in browsers) {
           var url = testingServer.getDriverUrl(browser.id);
           var future = browser.start(url).then((success) {
@@ skipping 366 matching lines @@
           // /favicon.ico requests
         }
         request.response.write(textResponse);
         request.listen((_) {}, onDone: request.response.close);
         request.response.done.catchError((error) {
           if (!underTermination) {
             print("URI ${request.uri}");
             print("Textresponse $textResponse");
             throw "Error returning content to browser: $error";
           }
-      });
+        });
       }
       void errorHandler(e) {
         if (!underTermination) print("Error occured in httpserver: $e");
       };
 
       httpServer.listen(handler, onError: errorHandler);
 
       // Set up the error reporting server that enables us to send back
       // errors from the browser.
       port = globalConfiguration['test_driver_error_port'];
@@ skipping 269 matching lines @@
     Dart test driver, number of tests: <div id="number"></div><br>
     Currently executing: <div id="currently_executing"></div><br>
     Unhandled error: <div id="unhandled_error"></div>
     <iframe id="embedded_iframe"></iframe>
   </body>
 </html>
 """;
     return driverContent;
   }
 }