Allow for reporting with the --list option

tools/testing/dart/test_configurations.dart

Index: tools/testing/dart/test_configurations.dart
===================================================================
--- tools/testing/dart/test_configurations.dart	(revision 42685)
+++ tools/testing/dart/test_configurations.dart	(working copy)
@@ -224,7 +224,9 @@
   }
 
   var eventListener = [];
-  if (progressIndicator != 'silent') {
+
+  // We don't print progress if we list tests.
+  if (progressIndicator != 'silent' && !listTests) {
     var printFailures = true;
     var formatter = new Formatter();
     if (progressIndicator == 'color') {
@@ -261,7 +263,13 @@
     eventListener.add(new UnexpectedCrashDumpArchiver());
   }
 
-  eventListener.add(new ExitCodeSetter());
+  // The only progress indicator when listing tests should be the
+  // the summary printer.
+  if (listTests) {
+    eventListener.add(new SummaryPrinter());
+  } else {
+    eventListener.add(new ExitCodeSetter());
+  }
 
   void startProcessQueue() {
     // [firstConf] is needed here, since the ProcessQueue needs to know the