Remove Expect from core library.

tests/language/getters_setters2_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.
 
+import "package:expect/expect.dart";
+
 // Tests classes with getters and setters that do not have the same type.
 
 class A {
   int a() { return 37;}
 }
 
 class B extends A{
   int b() { return 38; }
 }
 
@@ skipping 39 matching lines @@
 
   // Type 'A' has no method named 'b'
   instance1.field.b(); /// 02: static type warning
 
   instance3.field = new B();
   result = instance3.field.a();
   Expect.equals(37, result);
   result = instance3.field.b();
   Expect.equals(38, result);
 }