Migrated test block 29 to Dart 2.0

tests/corelib_strong/string_substring_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";
-
-main() {
-  // Test that not providing an optional argument goes to the end.
-  Expect.equals("".substring(0), "");
-  Expect.throws(() => "".substring(1), (e) => e is RangeError);
-  Expect.throws(() => "".substring(-1), (e) => e is RangeError);
-
-  Expect.equals("abc".substring(0), "abc");
-  Expect.equals("abc".substring(1), "bc");
-  Expect.equals("abc".substring(2), "c");
-  Expect.equals("abc".substring(3), "");
-  Expect.throws(() => "abc".substring(4), (e) => e is RangeError);
-  Expect.throws(() => "abc".substring(-1), (e) => e is RangeError);
-
-  // Test that providing null goes to the end.
-  Expect.equals("".substring(0, null), "");
-  Expect.throws(() => "".substring(1, null), (e) => e is RangeError);
-  Expect.throws(() => "".substring(-1, null), (e) => e is RangeError);
-
-  Expect.equals("abc".substring(0, null), "abc");
-  Expect.equals("abc".substring(1, null), "bc");
-  Expect.equals("abc".substring(2, null), "c");
-  Expect.equals("abc".substring(3, null), "");
-  Expect.throws(() => "abc".substring(4, null), (e) => e is RangeError);
-  Expect.throws(() => "abc".substring(-1, null), (e) => e is RangeError);
-}