Added support for logging the output of failed flaky tests.

tools/test.dart

 #!/usr/bin/env dart
 // Copyright (c) 2012, 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 63 matching lines @@
 
   // Extract global options from first configuration.
   var firstConf = configurations[0];
   Map<String, RegExp> selectors = firstConf['selectors'];
   var maxProcesses = firstConf['tasks'];
   var progressIndicator = firstConf['progress'];
   BuildbotProgressIndicator.stepName = firstConf['step_name'];
   var verbose = firstConf['verbose'];
   var printTiming = firstConf['time'];
   var listTests = firstConf['list'];
+  var appendFlakyLog = firstConf['append_flaky_log'];
+  
+  if (!appendFlakyLog)  {
+    var file = new File(FAILED_FLAKY_TESTS_LOGFILE);
+    if (file.existsSync()) {
+      file.deleteSync();
+    }
+  }
 
   // Print the configurations being run by this execution of
   // test.dart. However, don't do it if the silent progress indicator
   // is used. This is only needed because of the junit tests.
   if (progressIndicator != 'silent') {
     List output_words = configurations.length > 1 ?
         ['Test configurations:'] : ['Test configuration:'];
     for (Map conf in configurations) {
       List settings =
           ['compiler', 'runtime', 'mode', 'arch'].map((name) => conf[name]);
@@ skipping 44 matching lines @@
   // Start process queue.
   new ProcessQueue(maxProcesses,
                    progressIndicator,
                    startTime,
                    printTiming,
                    enqueueConfiguration,
                    () => terminateHttpServer(),
                    verbose,
                    listTests);
 }