Remove Expect from core library.

tests/language/static_field_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.
 // Dart test program for testing setting/getting/initializing static fields.
 
+import "package:expect/expect.dart";
+
 class First {
   First() {}
   static var a;
   static var b;
   static const int c = 1;
   static setValues() {
     a = 24;
     b = 10;
     return a + b + c;
   }
@@ skipping 90 matching lines @@
 }
 
 main() {
   StaticFieldTest.testMain();
   InitializerTest.testStaticFieldInitialization();
   new StaticField1RunNegativeTest().testMain();
   new StaticField1aRunNegativeTest().testMain();
   new StaticField2RunNegativeTest().testMain();
   new StaticField2aRunNegativeTest().testMain();
 }