Remove Expect from core library.

tests/compiler/dart2js/analyze_all_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.
 
+import "package:expect/expect.dart";
 import 'dart:uri';
 
 import 'compiler_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
        show MessageKind;
 
 const String SOURCE = """
 class Foo {
   // Deliberately not const to ensure compile error.
@@ skipping 31 matching lines @@
                 'expected exactly two errors, but got ${compiler.errors}');
 
   Expect.equals(MessageKind.CONSTRUCTOR_IS_NOT_CONST,
                 compiler.errors[0].message.kind);
   Expect.equals("Foo", compiler.errors[0].node.toString());
 
   Expect.equals(MessageKind.CONSTRUCTOR_IS_NOT_CONST,
                 compiler.errors[1].message.kind);
   Expect.equals("Foo", compiler.errors[1].node.toString());
 }