dart2js: run dartfmt on tests

tests/compiler/dart2js/unused_empty_map_test.dart

Index: tests/compiler/dart2js/unused_empty_map_test.dart
diff --git a/tests/compiler/dart2js/unused_empty_map_test.dart b/tests/compiler/dart2js/unused_empty_map_test.dart
index 5f806bca9b3c80a33c66ba3c53e4f863384c9724..8ba21680426b27b1f60a0a441e8c8444263cb350 100644
--- a/tests/compiler/dart2js/unused_empty_map_test.dart
+++ b/tests/compiler/dart2js/unused_empty_map_test.dart
@@ -8,12 +8,14 @@ import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'memory_compiler.dart';
 
-const TEST_SOURCE = const {"main.dart": r"""
+const TEST_SOURCE = const {
+  "main.dart": r"""
 void main() {
   var x = {};
   return;
 }
-"""};
+"""
+};
 
 const HASHMAP_EMPTY_CONSTRUCTOR = r"LinkedHashMap_LinkedHashMap$_empty";
 
@@ -21,7 +23,7 @@ main() {
   asyncTest(() async {
     var collector = new OutputCollector();
     var result = await runCompiler(
-      memorySourceFiles: TEST_SOURCE, outputProvider: collector);
+        memorySourceFiles: TEST_SOURCE, outputProvider: collector);
     var compiler = result.compiler;
     String generated = collector.getOutput('', 'js');
     Expect.isFalse(generated.contains(HASHMAP_EMPTY_CONSTRUCTOR));