Add clear_browser_cache flag to test.dart

tools/test.dart

 #!/usr/bin/env 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.
 
 /**
  * This file is the entrypoint of the dart test suite.  This suite is used
  * to test:
  *
  *     1. the dart vm
@@ skipping 67 matching lines @@
   // anymore.
   var failureSummary = firstConf['failure-summary'];
   BuildbotProgressIndicator.stepName = firstConf['step_name'];
   var verbose = firstConf['verbose'];
   var printTiming = firstConf['time'];
   var listTests = firstConf['list'];
 
   var recordingPath = firstConf['record_to_file'];
   var recordingOutputPath = firstConf['replay_from_file'];
 
-  // We set a special flag in the safari browser if we need to clear out
-  // the cache before running.
-  Safari.deleteCache = firstConf['clear_safari_cache'];
+  Browser.deleteCache = firstConf['clear_browser_cache'];
 
   if (recordingPath != null && recordingOutputPath != null) {
     print("Fatal: Can't have the '--record_to_file' and '--replay_from_file'"
           "at the same time. Exiting ...");
     exit(1);
   }
 
   if (!firstConf['append_logs'])  {
     var files = [new File(TestUtils.flakyFileName()),
                  new File(TestUtils.testOutcomeFileName())];
@@ skipping 208 matching lines @@
 void main(List<String> arguments) {
   deleteTemporaryDartDirectories().then((_) {
     var optionsParser = new TestOptionsParser();
     var configurations = optionsParser.parse(arguments);
     if (configurations != null && configurations.length > 0) {
       testConfigurations(configurations);
     }
   });
 }