Migrate test block 7 to Dart 2.0.

tests/corelib/double_round4_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';
-
-main() {
-  // The following numbers are on the border of 52 bits.
-  // For example: 4503599627370499 + 0.5 => 4503599627370500.
-  Expect.equals(4503599627370496, 4503599627370496.0.round());
-  Expect.equals(4503599627370497, 4503599627370497.0.round());
-  Expect.equals(4503599627370498, 4503599627370498.0.round());
-  Expect.equals(4503599627370499, 4503599627370499.0.round());
-
-  Expect.equals(9007199254740991, 9007199254740991.0.round());
-  Expect.equals(9007199254740992, 9007199254740992.0.round());
-
-  Expect.equals(-4503599627370496, (-4503599627370496.0).round());
-  Expect.equals(-4503599627370497, (-4503599627370497.0).round());
-  Expect.equals(-4503599627370498, (-4503599627370498.0).round());
-  Expect.equals(-4503599627370499, (-4503599627370499.0).round());
-
-  Expect.equals(-9007199254740991, (-9007199254740991.0).round());
-  Expect.equals(-9007199254740992, (-9007199254740992.0).round());
-
-  Expect.isTrue(4503599627370496.0.round() is int);
-  Expect.isTrue(4503599627370497.0.round() is int);
-  Expect.isTrue(4503599627370498.0.round() is int);
-  Expect.isTrue(4503599627370499.0.round() is int);
-  Expect.isTrue(9007199254740991.0.round() is int);
-  Expect.isTrue(9007199254740992.0.round() is int);
-  Expect.isTrue((-4503599627370496.0).round() is int);
-  Expect.isTrue((-4503599627370497.0).round() is int);
-  Expect.isTrue((-4503599627370498.0).round() is int);
-  Expect.isTrue((-4503599627370499.0).round() is int);
-  Expect.isTrue((-9007199254740991.0).round() is int);
-  Expect.isTrue((-9007199254740992.0).round() is int);
-}