Revert "Remove Expect from core library."

tests/standalone/deoptimization_test.dart

 // Copyright (c) 2011, 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 deoptimization.
 
-import "package:expect/expect.dart";
-
 class SmiCompares {
   // Test deoptimization when one argument is known to be Smi.
   static bool smiCompareLessThan2(a) {
     return a < 2;
   }
 
   // Test deoptimization when one argument is known to be Smi.
   static bool smiCompareGreaterThan2(a) {
     return 2 < a;
   }
@@ skipping 187 matching lines @@
     SmiBinop.smiBinopOverflowTest();
     ObjectsEquality.objectsEqualityTest();
     smiRightShift();
     doubleUnary();
   }
 }
 
 main() {
   DeoptimizationTest.testMain();
 }