dart2js: run dartfmt on tests

tests/compiler/dart2js/serialization/duplicate_library_test.dart

Index: tests/compiler/dart2js/serialization/duplicate_library_test.dart
diff --git a/tests/compiler/dart2js/serialization/duplicate_library_test.dart b/tests/compiler/dart2js/serialization/duplicate_library_test.dart
index 3380c66be35b8d1193717ebbf5f55b2f3843e6d1..290a704f6c4e7489ab752ca6f93567e8cbd4fee3 100644
--- a/tests/compiler/dart2js/serialization/duplicate_library_test.dart
+++ b/tests/compiler/dart2js/serialization/duplicate_library_test.dart
@@ -17,8 +17,8 @@ import 'test_data.dart';
 
 void main(List<String> args) {
   asyncTest(() async {
-    SerializedData data = await serializeDartCore(
-        arguments: new Arguments.from(args));
+    SerializedData data =
+        await serializeDartCore(arguments: new Arguments.from(args));
     Map<String, String> sourceFiles = data.toMemorySourceFiles();
     List<Uri> resolutionInputs = data.toUris();
     Uri extraUri = Uri.parse('memory:extraUri');
@@ -35,4 +35,4 @@ void main(List<String> args) {
     Expect.isTrue(collector.errors.isNotEmpty,
         "Expected duplicate serialized library errors.");
   });
-}
+}