Migrate test block 7 to Dart 2.0.

tests/corelib_strong/duration_big_num_test.dart

Index: tests/corelib_strong/duration_big_num_test.dart
diff --git a/tests/corelib_strong/duration_big_num_test.dart b/tests/corelib_strong/duration_big_num_test.dart
deleted file mode 100644
index 154afb90734db126270a4a3cd01748a4f7532b60..0000000000000000000000000000000000000000
--- a/tests/corelib_strong/duration_big_num_test.dart
+++ /dev/null
@@ -1,21 +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";
-import 'dart:math';
-
-main() {
-  Duration d, d1;
-
-  d1 = new Duration(microseconds: pow(2, 53));
-  d = d1 * 2;
-  Expect.equals(pow(2, 54), d.inMicroseconds);
-  d = d1 * 1.5;
-  Expect.equals(pow(2, 53).toDouble() * 1.5, d.inMicroseconds);
-  Expect.isTrue(d.inMicroseconds is int);
-
-  // Test that we lose precision when multiplying with a double.
-  d = new Duration(microseconds: pow(2, 53) + 1) * 1.0;
-  Expect.equals(0, d.inMicroseconds % 2);
-}