Remove Expect from core library.

tests/language/allocate_test.dart

Index: tests/language/allocate_test.dart
diff --git a/tests/language/allocate_test.dart b/tests/language/allocate_test.dart
index db621672d54bce8ef824516f45cf6739d92a843a..1f2fce2a6ba2ce5bbfa6b567ed681e4bf49455fa 100644
--- a/tests/language/allocate_test.dart
+++ b/tests/language/allocate_test.dart
@@ -1,6 +1,9 @@
 // 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";
+
 class MyAllocate {
   const MyAllocate([int value = 0]) : value_ = value;
   int getValue() { return value_; }