Handle explicit constructor.

tests/compiler/dart2js/serialization/compilation_test.dart

Index: tests/compiler/dart2js/serialization/compilation_test.dart
diff --git a/tests/compiler/dart2js/serialization/compilation_test.dart b/tests/compiler/dart2js/serialization/compilation_test.dart
index 4bb7467ab6a9119ab84bcf25052d9bb0c1195acb..7d9cce2c7d05bc4b4550810fb1e652f039b9c643 100644
--- a/tests/compiler/dart2js/serialization/compilation_test.dart
+++ b/tests/compiler/dart2js/serialization/compilation_test.dart
@@ -27,14 +27,11 @@ main(List<String> args) {
       await compile(serializedData, entryPoint, null);
     } else {
       Uri entryPoint = Uri.parse('memory:main.dart');
-      int start = arguments.index ?? 0;
-      int end = arguments.index ?? TESTS.length - 1;
-      for (int index = start; index <= end; index++) {
-        Test test = TESTS[index];
+      arguments.forEachTest(TESTS, (int index, Test test) async {
         await compile(serializedData, entryPoint, test,
                       index: index,
                       verbose: arguments.verbose);
-      }
+      });
     }
   });
 }