Revert "Remove Expect from core library."

tests/language/type_vm_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.
 // VMOptions=--enable_type_checks --no_show_internal_names
+//
 // Dart test program testing type checks.
-import "package:expect/expect.dart";
 
 class TypeTest {
   static test() {
     int result = 0;
     try {
       int i = "hello";  // Throws a TypeError if type checks are enabled.
     } on TypeError catch (error) {
       result = 1;
       Expect.equals("int", error.dstType);
       Expect.equals("String", error.srcType);
@@ skipping 541 matching lines @@
 class C {
   factory C() {
     return 1;  // Implicit result type is 'C', not int.
   }
 }
 
 
 main() {
   TypeTest.testMain();
 }