Revert "Remove Expect from core library."

tests/language/function_type_alias2_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
 //
 // Dart test for function type alias with optional parameters.
 
-import "package:expect/expect.dart";
-
 typedef int f1<T>([int a, int b, T c]);
 typedef int f2<T>([int a, int b, T d]);
 typedef int f3<T>({int a, int b, T c});
 typedef int f4<T>({int a, int b, T d});
 
 class A<T> {
   int baz([int a, int b, T c]) { }
   int bar({int a, int b, T c}) { }
 }
 
@@ skipping 24 matching lines @@
   Expect.isTrue(a.baz is f1);
   Expect.isTrue(a.baz is f1<int>);
   Expect.isTrue(a.bar is f3<int>);
   Expect.isFalse(a.baz is f1<double>);
   Expect.isFalse(a.bar is f3<double>);
   Expect.isTrue(a.baz is f2);
   Expect.isFalse(a.bar is f4);
   Expect.isTrue(a.baz is f2<int>);
   Expect.isFalse(a.bar is f2<int>);
 }