Remove corelib/corelib_strong and migrate last two remaining tests.

tests/corelib/double_ceil2_test.dart

Index: tests/corelib/double_ceil2_test.dart
diff --git a/tests/corelib/double_ceil2_test.dart b/tests/corelib/double_ceil2_test.dart
deleted file mode 100644
index b82daec3482846fb3a589f3b11454a5fb194d239..0000000000000000000000000000000000000000
--- a/tests/corelib/double_ceil2_test.dart
+++ /dev/null
@@ -1,12 +0,0 @@
-// 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';
-
-main() {
-  Expect.throws(() => double.INFINITY.ceil(), (e) => e is UnsupportedError);
-  Expect.throws(
-      () => double.NEGATIVE_INFINITY.ceil(), (e) => e is UnsupportedError);
-  Expect.throws(() => double.NAN.ceil(), (e) => e is UnsupportedError);
-}