Revert "Remove Expect from core library."

tests/standalone/left_shift_bit_and_op_test.dart

 // Copyright (c) 2013, 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.
 //
 // Tests optimizing (a << b) & c if c is a Smi constant.
 
-import "package:expect/expect.dart";
-
 main() {
   checkshiftAnd32();
   checkShiftAnd64();
   // Optimize shiftAnd32.
   for (int i = 0; i < 10000; i++) {
     A.shiftAnd32(12, 17);
     A.shiftAnd64(12, 17);
     Expect.equals(72, A.multipleConstantUses(3, 4));
     Expect.equals(34493956096, A.multipleShiftUse(134742016, 8));
   }
@@ skipping 49 matching lines @@
   }
 
   foo(x) { return x & 0xf; }
 }
 
 class B { foo(x) { return x; } }
 
 bar (o) {
   return o.foo(1 << 32);
 }