Remove Expect from core library.

tests/language/bool_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.
 
+import "package:expect/expect.dart";
+
 // Dart test program for testing basic boolean properties.
 // @static-clean
 
 class BoolTest {
   static void testEquality() {
     Expect.equals(true, true);
     Expect.equals(false, false);
     Expect.isTrue(identical(true, true));
     Expect.isFalse(identical(true, false));
     Expect.isTrue(identical(false, false));
@@ skipping 195 matching lines @@
     testEquality();
     testNegate(true, false);
     testToString();
     testLogicalOp();
   }
 }
 
 main() {
   BoolTest.testMain();
 }