Fix some tests.

tests/compiler/dart2js/simple_inferrer_postfix_prefix_test.dart

 // Copyright (c) 2013, 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.
 
+import 'package:expect/expect.dart';
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
 
 const String TEST = """
 
 class A {
   get foo => 'string';
   set foo(value) {}
   operator[](index) => 'string';
   operator[]=(index, value) {}
@@ skipping 69 matching lines @@
   checkReturnInClass('A', 'returnDynamic2', subclassOfInterceptor);
   checkReturnInClass('A', 'returnDynamic3', typesInferrer.dynamicType);
 
   checkReturnInClass('B', 'returnString1', typesInferrer.stringType);
   checkReturnInClass('B', 'returnString2', typesInferrer.stringType);
   checkReturnInClass('B', 'returnDynamic1', typesInferrer.dynamicType);
   checkReturnInClass('B', 'returnDynamic2', typesInferrer.dynamicType);
   checkReturnInClass('B', 'returnDynamic3', typesInferrer.dynamicType);
   checkReturnInClass('B', 'returnDynamic4', typesInferrer.dynamicType);
 }