Revert "Remove Expect from core library."

tests/language/optimize_redundant_array_load_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.
 
-import "package:expect/expect.dart";
-
 // Test optimization of redundant array loads.
 
 var A = [0,2,3];
 
 test1(a) {
   int x = a[0];
   int y = a[1];
   ++a[0];
   return a[0] + y + a[2];
 }
 
 
 int test2(a) {
   return a[2] + a[2];
 }
 
 
 main() {
   for (int i = 0; i < 10000; i++) {
     test1(A);
     test2(A);
   }
   Expect.equals(10006, test1(A));
   Expect.equals(6, test2(A));
 }