Remove Expect from core library.

tests/corelib/string_from_list_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";
+
 class StringFromListTest {
   static testMain() {
     Expect.equals("", new String.fromCharCodes(new List.fixedLength(0)));
     Expect.equals("", new String.fromCharCodes([]));
     Expect.equals("", new String.fromCharCodes(const []));
     Expect.equals("AB", new String.fromCharCodes([65, 66]));
     Expect.equals("AB", new String.fromCharCodes(const [65, 66]));
     Expect.equals("Ærø", new String.fromCharCodes(const [0xc6, 0x72, 0xf8]));
     Expect.equals("\u{1234}", new String.fromCharCodes([0x1234]));
     Expect.equals("\u{12345}*", new String.fromCharCodes([0x12345, 42]));
@@ skipping 23 matching lines @@
       middle -= middle % 26;
       Expect.equals('XYZABC', long.substring(middle - 3, middle + 3));
       Expect.equals(len, long.length);
     }
   }
 }
 
 main() {
   StringFromListTest.testMain();
 }