Handle explicit constructor.

tests/compiler/dart2js/serialization/model_test.dart

Index: tests/compiler/dart2js/serialization/model_test.dart
diff --git a/tests/compiler/dart2js/serialization/model_test.dart b/tests/compiler/dart2js/serialization/model_test.dart
index 1ae29d8de696b4a038c2beae2692fae8a7c4cdee..248c500fba8bd63b01d3f5ea50c53b7a9d9f0965 100644
--- a/tests/compiler/dart2js/serialization/model_test.dart
+++ b/tests/compiler/dart2js/serialization/model_test.dart
@@ -42,7 +42,7 @@ main(List<String> args) {
       await checkModels(serializedData, entryPoint);
     } else {
       Uri entryPoint = Uri.parse('memory:main.dart');
-      for (Test test in TESTS) {
+      arguments.forEachTest(TESTS, (int index, Test test) async {
         print('==============================================================');
         print(test.sourceFiles);
         await checkModels(
@@ -50,7 +50,7 @@ main(List<String> args) {
           entryPoint,
           sourceFiles: test.sourceFiles,
           verbose: arguments.verbose);
-      }
+      });
     }
   });
 }