Revert "Remove Expect from core library."

tests/compiler/dart2js/type_inference5_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.
 
-import "package:expect/expect.dart";
 import 'compiler_helper.dart';
 
 const String TEST_ONE = r"""
 foo(j) {
   var a = [1, 2, 3];
   for (var i = j; i < 3; i++) {
     a[i];
   }
 }
 """;
 
 main() {
   String generated = compile(TEST_ONE, entry: 'foo');
 
   // Test for absence of an illegal argument exception. This means that the
   // arguments are known to be integers.
   Expect.isFalse(generated.contains('iae'));
   // Also make sure that we are not just in bailout mode without speculative
   // types by grepping for the integer-bailout check on argument j.
   var argname =
       new RegExp(r'function(?: [a-z]+)?\(([a-zA-Z0-9_]+)\)').firstMatch(generated)[1];
   print(argname);
   RegExp regexp = new RegExp(getIntTypeCheck(argname));
   Expect.isTrue(regexp.hasMatch(generated));
 }