Remove Expect from core library.

runtime/tests/vm/dart/byte_array_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 be able to run in html test framework.
 library byte_array_test;
 
+import "package:expect/expect.dart";
 import 'dart:scalarlist';
 
 class ByteArrayTest {
   static testInt8ListImpl(Int8List array) {
     Expect.isTrue(array is List<int>);
     Expect.equals(10, array.length);
     Expect.equals(1, array.bytesPerElement());
     Expect.equals(10, array.lengthInBytes());
     Expect.listEquals([0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0],
@@ skipping 2382 matching lines @@
     testInt64ListView();
     testUint64ListView();
     testFloat32ListView();
     testFloat64ListView();
   }
 }
 
 main() {
   ByteArrayTest.testMain();
 }