tools/test.dart: Add summary report of the number of tests with each expectation.

tools/testing/dart/test_options.dart

Index: tools/testing/dart/test_options.dart
diff --git a/tools/testing/dart/test_options.dart b/tools/testing/dart/test_options.dart
index aa8744f1610b4ea04e3c07d5e3fb0675604d7b6c..f0e397d3c51111d6e8296990fd7b2a03b0cc0348 100644
--- a/tools/testing/dart/test_options.dart
+++ b/tools/testing/dart/test_options.dart
@@ -85,6 +85,13 @@ class TestOptionsParser {
               ['compact', 'line', 'verbose', 'status', 'buildbot'],
               'compact'),
           new _TestOptionSpecification(
+              'report',
+              'Print a summary report of the number of tests, by expectation.',
+              ['--report'],
+              [],
+              false,
+              'bool'),
+          new _TestOptionSpecification(
               'tasks',
               'The number of parallel tasks to run',
               ['-j', '--tasks'],