Added json result of test output to output debug directory.

tools/testing/dart/test_configurations.dart

Index: tools/testing/dart/test_configurations.dart
diff --git a/tools/testing/dart/test_configurations.dart b/tools/testing/dart/test_configurations.dart
index 7b9be0e1e9490b252afc3e50297c8d8ab753137a..8b0542aeda6e4a7c9acb062bcf7276df5138ccd9 100644
--- a/tools/testing/dart/test_configurations.dart
+++ b/tools/testing/dart/test_configurations.dart
@@ -233,6 +233,10 @@ Future testConfigurations(List<Configuration> configurations) async {
     eventListener.add(new TestOutcomeLogWriter());
   }
 
+  if (firstConf.writeResultJsonLog) {
+    eventListener.add(new TestResultLogWriter());

[Bill Hesse, 2017/09/01 11:56:13]

ResultLogWriter

[mkroghj, 2017/09/04 10:43:34]

Done.

+  }
+
   if (firstConf.copyCoreDumps) {
     eventListener.add(new UnexpectedCrashLogger());
   }