Retry failing tests on Safari, because it is flaky.

tools/testing/dart/test_runner.dart

Index: tools/testing/dart/test_runner.dart
diff --git a/tools/testing/dart/test_runner.dart b/tools/testing/dart/test_runner.dart
index fd2922090313ec6e541fcf8600057fd9ecb81331..befa478fe6b86a455ff86d1bbbff190801136335 100644
--- a/tools/testing/dart/test_runner.dart
+++ b/tools/testing/dart/test_runner.dart
@@ -2581,6 +2581,13 @@ class ReplayingCommandExecutor implements CommandExecutor {
 
 bool shouldRetryCommand(CommandOutput output) {
   var command = output.command;
+  // We rerun tests on Safari because 6.2 and 7.1 are flaky. Issue 21434.
+  if (command is BrowserTestCommand && command.browser == 'safari' &&
+      output is BrowserControllerTestOutcome &&
+      output._rawOutcome != Expectation.PASS) {
+    // TODO(whesse): This retries tests that fail intentionally. Fix this
+    return true;
+  }
 
   if (!output.successful) {
     List<String> stdout, stderr;
@@ -2606,9 +2613,7 @@ bool shouldRetryCommand(CommandOutput output) {
     }
 
     // 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')) {
+    if (command is BrowserTestCommand && command.browser == 'dartium') {
       return true;
     }
   }