Revert "Remove Expect from core library."

tests/lib/crypto/sha1_test.dart

 // Copyright (c) 2012, 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 tag to allow dartium to run the test.
 library sha1_test;
 
-import "package:expect/expect.dart";
 import 'dart:crypto';
 
 part 'sha1_long_test_vectors.dart';
 part 'sha1_short_test_vectors.dart';
 
 List<int> createTestArr(int len) {
   var arr = new List<int>(len);
   for (var i = 0; i < len; i++) {
     arr[i] = i;
   }
@@ skipping 544 matching lines @@
   }
 }
 
 void main() {
   test();
   testInvalidUse();
   testRepeatedDigest();
   testStandardVectors(sha1_long_inputs, sha1_long_mds);
   testStandardVectors(sha1_short_inputs, sha1_short_mds);
 }