dart2js: run dartfmt on tests

tests/compiler/dart2js/benign_error_test.dart

Index: tests/compiler/dart2js/benign_error_test.dart
diff --git a/tests/compiler/dart2js/benign_error_test.dart b/tests/compiler/dart2js/benign_error_test.dart
index 28c84dd658cd2fb5e69fd3ebf6f0f1d2a9eaecb2..143239b3b162c4e6e41f8dea159fb5966559bbe7 100644
--- a/tests/compiler/dart2js/benign_error_test.dart
+++ b/tests/compiler/dart2js/benign_error_test.dart
@@ -28,13 +28,12 @@ testExamples(MessageKind kind) async {
     }
     DiagnosticCollector collector = new DiagnosticCollector();
     CompilationResult result = await runCompiler(
-        memorySourceFiles: example,
-        diagnosticHandler: collector);
+        memorySourceFiles: example, diagnosticHandler: collector);
     Expect.isTrue(result.isSuccess);
-    Expect.isTrue(
-        collector.errors.any((message) => message.messageKind == kind));
+    Expect
+        .isTrue(collector.errors.any((message) => message.messageKind == kind));
     Compiler compiler = result.compiler;
     JavaScriptBackend backend = compiler.backend;
     Expect.isNotNull(backend.generatedCode[compiler.mainFunction]);
   }
-}
+}