Move minitest.dart into the expect package.

pkg/dev_compiler/test/codegen/lib/html/js_typed_interop_anonymous_unreachable_test.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.
 
 @JS()
 library js_typed_interop_anonymous_unreachable_test;
 
 import 'dart:html';
 import 'dart:js' as js;
 
 import 'package:js/js.dart';
-import 'package:minitest/minitest.dart';
+import 'package:expect/minitest.dart';
 
 @JS() @anonymous
 class Literal {
   external factory Literal({int x, String y, num z});
 
   external int get x;
   external String get y;
   external num get z;
 }
 
 main() {
   test('nothing to do', () {
     // This test is empty, but it is a regression for Issue# 24974: dartjs
     // would crash trying to compile code that used @anonymous and that was
     // not reachable from main.
   });
 }