Use JS backend in serialization_analysis_test

pkg/compiler/lib/src/serialization/keys.dart

 // Copyright (c) 2015, 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.serialization.keys;
 
 /// Keys used for serialization.
 class Key {
   static const Key ALIAS = const Key('alias');
   static const Key ARGUMENTS = const Key('arguments');
@@ skipping 25 matching lines @@
   static const Key INTERFACES = const Key('interfaces');
   static const Key INDEX = const Key('index');
   static const Key IS_ABSTRACT = const Key('isAbstract');
   static const Key IS_CONST = const Key('isConst');
   static const Key IS_DEFERRED = const Key('isDeferred');
   static const Key IS_EXTERNAL = const Key('isExternal');
   static const Key IS_FINAL = const Key('isFinal');
   static const Key IS_NAMED = const Key('isNamed');
   static const Key IS_OPERATOR = const Key('isOperator');
   static const Key IS_OPTIONAL = const Key('isOptional');
+  static const Key IS_UNNAMED_MIXIN_APPLICATION =
+      const Key('isUnnamedMixinApplication');
   static const Key KEYS = const Key('keys');
   static const Key KIND = const Key('kind');
   static const Key LEFT = const Key('left');
   static const Key LENGTH = const Key('length');
   static const Key LIBRARY = const Key('library');
   static const Key LIBRARY_DEPENDENCY = const Key('library-dependency');
   static const Key LIBRARY_NAME = const Key('library-name');
   static const Key MEMBERS = const Key('members');
   static const Key NAME = const Key('name');
   static const Key NAMES = const Key('names');
@@ skipping 21 matching lines @@
   static const Key URI = const Key('uri');
   static const Key VALUE = const Key('value');
   static const Key VALUES = const Key('values');
 
   final String name;
 
   const Key(this.name);
 
   String toString() => name;
 }