Revert "Remove Expect from core library."

tests/standalone/typed_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.
 //
 // Dart test program for testing native float arrays.
 
 // Library tag to be able to run in html test framework.
 library TypedArray;
-import "package:expect/expect.dart";
 import 'dart:isolate';
 import 'dart:typeddata';
 
 void main() {
   int8_receiver();
   uint8_receiver();
   int16_receiver();
   uint16_receiver();
   int32_receiver();
   uint32_receiver();
@@ skipping 314 matching lines @@
 float64_sender() {
   port.receive((len, r) {
     Expect.equals(float64.length, len);
     var a = new Float64List(len);
     for (int i = 0; i < len; i++) {
       a[i] = float64[i];
     }
     r.send(a);
   });
 }