Fix Browser Controller to not reuse iFrames, which can sometimes cause bad state to be left between…

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 1356 matching lines @@
         // negative value.
         contactBrowserController(
             'GET', '$nextTestPath/$browserId', newTaskHandler, "", false);
       }
 
       function run(url) {
         number_of_tests++;
         number_div.innerHTML = number_of_tests;
         executing_div.innerHTML = url;
         if (use_iframe) {
+          var embedded_iframe = document.getElementById('embedded_iframe');
+          embedded_iframe.parentNode.removeChild(embedded_iframe);
+
+          embedded_iframe = document.createElement('iframe');
+          embedded_iframe.id = 'embedded_iframe';
+          document.body.appendChild(embedded_iframe);
           embedded_iframe.src = url;
         } else {
-          if (testing_window == undefined) {
-            testing_window = window.open(url);
-          } else {
-            testing_window.location = url;
+          if (typeof testing_window != 'undefined') {
+            testing_window.close();
           }
+          testing_window = window.open(url);
         }
       }
 
       window.onerror = function (message, url, lineNumber) {
         if (url) {
           reportError(url + ':' + lineNumber + ':' + message);
         } else {
           reportError(message);
         }
       }
@@ skipping 100 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;
   }
 }