Move minitest.dart into the expect package.

pkg/dev_compiler/test/codegen/lib/html/js_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 'dart:html';
 import 'dart:typed_data' show ByteBuffer, Int32List;
 import 'dart:indexed_db' show IdbFactory, KeyRange;
 import 'dart:js';
 
-import 'package:minitest/minitest.dart';
+import 'package:expect/minitest.dart';
 
 _injectJs() {
   final script = new ScriptElement();
   script.type = 'text/javascript';
   script.innerHtml = r"""
 var x = 42;
 
 var _x = 123;
 
 var myArray = ["value1"];
@@ skipping 977 matching lines @@
           // expect(context.callMethod('isPropertyInstanceOf', ['o', listType]),
           //    isTrue);
           context.deleteProperty('o');
         }
       });
 
     });
   });
 
 }