Move minitest.dart into the expect package.

pkg/dev_compiler/test/codegen/lib/html/element_offset_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:async';
 import 'dart:html';
 
-import 'package:minitest/minitest.dart';
+import 'package:expect/minitest.dart';
 
 main() {
   void initPage() {
     var level1 = new UListElement()
       ..classes.add('level-1')
       ..children.add(new LIElement()..innerHtml = 'I');
     var itemii = new LIElement()
       ..classes.add('item-ii')
       ..style.position = 'relative'
       ..style.top = '4px'
@@ skipping 109 matching lines @@
       expect(baz.documentOffset.y, 608);
 
       expect(qux.documentOffset.x, 8);
       expect(qux.documentOffset.y, inInclusiveRange(203, 240));
 
       expect(quux.documentOffset.x, 8);
       expect(quux.documentOffset.y, inInclusiveRange(203, 240));
     });
   });
 }