Revert "Remove Expect from core library."

tests/language/optimized_lists_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.
 // Test program for correct optimizations related to types fo allocated lists.
 
-import "package:expect/expect.dart";
-
 main() {
   // Trigger optimization of 'test' method.
   for (int i = 0; i < 1000; i++) {
     test(2);
   }
 }
 
 
 test(n) {
   var a = new List();    // Growable list.
   var b = new List(10);  // Fixed size list.
   var c = const [1, 2, 3, 4];  // Constant aray.
   // In optimized mode the class checks will be eliminated since the
   // constructors above provide information about exact types.
   a.add(4);
   b[0] = 5;
   Expect.equals(4, a[0]);
   Expect.equals(5, b[0]);
   // Test bound check elimination.
   Expect.equals(2, c[1]);
   // Test elimination of array length computation.
   var v = c[n];
   Expect.equals(v, c[n]);
 }