Remove Expect from core library.

tests/language/many_calls_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 megamorphic calls.
 
+import "package:expect/expect.dart";
+
 class A {
   A() {}
   f1() { return 1; }
   f2() { return 2; }
   f3() { return 3; }
   f4() { return 4; }
   f5() { return 5; }
   f6() { return 6; }
   f7() { return 7; }
   f8() { return 8; }
@@ skipping 85 matching lines @@
         Expect.equals(38, list[i].f38());
         Expect.equals(39, list[i].f39());
       }
     }
   }
 }
 
 main() {
   ManyCallsTest.testMain();
 }