dart2js: run dartfmt on tests

tests/compiler/dart2js/kernel/impact_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.kernel.impact_test;
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 146 matching lines @@
 '''
 };
 
 main(List<String> args) {
   asyncTest(() async {
     enableDebugMode();
     Uri entryPoint = Uri.parse('memory:main.dart');
     Compiler compiler = compilerFor(
         entryPoint: entryPoint,
         memorySourceFiles: SOURCE,
-        options:
-            [Flags.analyzeAll, Flags.useKernel, Flags.enableAssertMessage]);
+        options: [
+          Flags.analyzeAll,
+          Flags.useKernel,
+          Flags.enableAssertMessage
+        ]);
     compiler.resolution.retainCachesForTesting = true;
     await compiler.run(entryPoint);
     checkLibrary(compiler, compiler.mainApp);
   });
 }
 
 void checkLibrary(Compiler compiler, LibraryElement library) {
   library.forEachLocalMember((AstElement element) {
     if (element.isClass) {
       // TODO(johnniwinther): Handle class members.
     } else {
       checkElement(compiler, element);
     }
   });
 }
 
 void checkElement(Compiler compiler, AstElement element) {
   ResolutionImpact astImpact = compiler.resolution.getResolutionImpact(element);
   ResolutionImpact kernelImpact = build(compiler, element.resolvedAst);
   testResolutionImpactEquivalence(
       astImpact, kernelImpact, const CheckStrategy());
 }