Added support for logging the output of failed flaky tests.

tools/test-runtime.dart

Index: tools/test-runtime.dart
diff --git a/tools/test-runtime.dart b/tools/test-runtime.dart
index b9663ffe0cab54ad2933118a25332976f3ff5e89..3bcdac3fea9d116dee37f0021bc4d13c444d039e 100755
--- a/tools/test-runtime.dart
+++ b/tools/test-runtime.dart
@@ -11,6 +11,7 @@
 #library("test");
 
 #import("dart:io");
+#import("testing/dart/test_progress.dart");
 #import("testing/dart/test_runner.dart");
 #import("testing/dart/test_options.dart");
 #import("testing/dart/test_suite.dart");
@@ -50,7 +51,14 @@ main() {
   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.