Clear 'referenceMap' before summarizing a new unit.

pkg/analyzer/test/src/test_all.dart

Index: pkg/analyzer/test/src/test_all.dart
diff --git a/pkg/analyzer/test/src/test_all.dart b/pkg/analyzer/test/src/test_all.dart
index b97bc818f66361295a236f673d7052d63bf01e4d..14226d878b9940c5669b2bb0d19c834523c8b5bf 100644
--- a/pkg/analyzer/test/src/test_all.dart
+++ b/pkg/analyzer/test/src/test_all.dart
@@ -9,6 +9,7 @@ import 'package:unittest/unittest.dart';
 import '../utils.dart';
 import 'context/test_all.dart' as context;
 import 'plugin/plugin_config_test.dart' as plugin;
+import 'summary/test_all.dart' as summary;
 import 'task/test_all.dart' as task;
 import 'util/test_all.dart' as util;
 
@@ -18,6 +19,7 @@ main() {
   group('src tests', () {
     context.main();
     plugin.main();
+    summary.main();
     task.main();
     util.main();
   });