Revert "Remove Expect from core library."

tests/language/built_in_identifier_prefix_test.dart

 // Copyright (c) 2012, 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 that built-in identifiers can be used as library prefixes.
 
 // From The Dart Programming Language Specification, section 11.30
 // "Identifier Reference":
 //
 // "A built-in identifier is one of the identifiers produced by the
 // production BUILT IN IDENTIFIER. It is a compile-time error if a
 // built-in identifier is used as the declared name of a class, type
 // parameter or type alias. It is a compile-time error to use a
 // built-in identifier other than dynamic as a type annotation."
 //
 // Observation: it is not illegal to use a built-in identifier as a library
 // prefix.
 //
 // Observation: it is not legal to use a built-in identifer as a type
 // annotation. A type annotation is not fully defined in the
 // specification, so we assume this means that the grammar production
 // "type" cannot match a built-in identifier. Unfortunately, this
 // doesn't prevent us from using built-in identifiers *in* type
 // annotations. For example, "final abstract foo;" is illegal as
 // "abstract" is used as a type annotation. However, "final
 // abstract<dynamic> foo;" is not illegal because "abstract" is used
 // as a typeName.
 
-import "package:expect/expect.dart";
 import 'built_in_identifier_prefix_library_abstract.dart' as abstract;
 import 'built_in_identifier_prefix_library_as.dart' as as;
 import 'built_in_identifier_prefix_library_dynamic.dart' as dynamic;
 import 'built_in_identifier_prefix_library_export.dart' as export;
 import 'built_in_identifier_prefix_library_external.dart' as external;
 import 'built_in_identifier_prefix_library_factory.dart' as factory;
 import 'built_in_identifier_prefix_library_get.dart' as get;
 import 'built_in_identifier_prefix_library_implements.dart' as implements;
 import 'built_in_identifier_prefix_library_import.dart' as import;
 import 'built_in_identifier_prefix_library_library.dart' as library;
@@ skipping 167 matching lines @@
   Expect.isTrue(parameterized_B_get is get.B);
   Expect.isTrue(parameterized_B_implements is implements.B);
   Expect.isTrue(parameterized_B_import is import.B);
   Expect.isTrue(parameterized_B_library is library.B);
   Expect.isTrue(parameterized_B_operator is operator.B);
   Expect.isTrue(parameterized_B_part is part.B);
   Expect.isTrue(parameterized_B_set is set.B);
   Expect.isTrue(parameterized_B_static is static.B);
   Expect.isTrue(parameterized_B_typedef is typedef.B);
 }