Remove Expect from core library.

tests/lib/async/stream_min_max_test.dart

 // Copyright (c) 2011, 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 stream_min_max_test;
 
+import "package:expect/expect.dart";
 import 'dart:async';
 import 'dart:isolate';
 import '../../../pkg/unittest/lib/unittest.dart';
 import 'event_helper.dart';
 
 const int big = 1000000;
 const double inf = double.INFINITY;
 List intList = const [-0, 0, -1, 1, -10, 10, -big, big];
 List doubleList = const [-0.0, 0.0, -1.0, 1.0, -10.0, 10.0, -inf, inf];
 
@@ skipping 18 matching lines @@
   testMinMax("set-int", intList.toSet(), -big, big);
 
   testMinMax("const-double", doubleList, -inf, inf);
   testMinMax("list-double", doubleList.toList(), -inf, inf);
   testMinMax("set-double", doubleList.toSet(), -inf, inf);
 
   int reverse(a, b) => b.compareTo(a);
   testMinMax("rev-int", intList, big, -big, reverse);
   testMinMax("rev-double", doubleList, inf, -inf, reverse);
 }