Remove Expect from core library.

tests/standalone/io/file_invalid_arguments_test.dart

 // Copyright (c) 2013, 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:io";
 import "dart:isolate";
 
 void testReadInvalidArgs(arg) {
   var port = new ReceivePort();
   String filename = getFilename("tests/vm/data/fixed_length_file");
   var file = (new File(filename)).openSync();
   try {
     file.readSync(arg);
     Expect.fail('exception expected');
@@ skipping 122 matching lines @@
   testReadInvalidArgs('asdf');
   testReadListInvalidArgs(12, 0, 1);
   testReadListInvalidArgs(new List(10), '0', 1);
   testReadListInvalidArgs(new List(10), 0, '1');
   testWriteByteInvalidArgs('asdf');
   testWriteListInvalidArgs(12, 0, 1);
   testWriteListInvalidArgs(new List(10), '0', 1);
   testWriteListInvalidArgs(new List(10), 0, '1');
   testWriteStringInvalidArgs("Hello, world", 42);
 }