Revert "Remove Expect from core library."

tests/language/local_function_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.
 // Dart test program testing closures.
 
-import "package:expect/expect.dart";
-
 class LocalFunctionTest {
   LocalFunctionTest() : field1 = 100, field2_ = 200  { }
   static int f(int n) {
     int a = 0;
     g(int m) {
       a = 3*n + m + 1;  // Capture parameter n and local a.
       return a;
     }
     var b = g(n);
     return a + b;
@@ skipping 167 matching lines @@
     Expect.equals(24*25/2, testNesting(5));
     Expect.equals(true, testClosureCallStatement(7));
     Expect.equals(99, doThis(10, (n) => n * n - 1));
     testExceptions();
   }
 }
 
 main() {
   LocalFunctionTest.testMain();
 }