Retry flaky tests on Safari.

tools/testing/dart/test_runner.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.
 
 /**
  * Classes and methods for executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 2587 matching lines @@
       // "xvfb-run" issue 7564, try re-running the test.
       bool containsFailureMsg(String line) {
         return line.contains(MESSAGE_CANNOT_OPEN_DISPLAY) ||
                line.contains(MESSAGE_FAILED_TO_RUN_COMMAND);
       }
       if (stdout.any(containsFailureMsg) || stderr.any(containsFailureMsg)) {
         return true;
       }
     }
 
-    // We currently rerun dartium tests, see issue 14074
-    if (command is BrowserTestCommand && command.displayName == 'dartium') {
+    // We currently rerun dartium tests, see issue 14074.
+    // We rerun tests on Safari because 6.2 and 7.1 are flaky. Issue 21434.
+    if (command is BrowserTestCommand &&
+        (command.browser == 'dartium' || command.browser == 'safari')) {
       return true;
     }
   }
   return false;
 }
 
 /*
  * [TestCaseCompleter] will listen for
  * NodeState.Processing -> NodeState.{Successful,Failed} state changes and
  * will complete a TestCase if it is finished.
@@ skipping 281 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
     _allDone();
   }
 }