Migrated test block 19 to Dart 2.0.

tests/corelib/regexp/default_arguments_test.dart

-// Copyright (c) 2015, 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.
-
-// Test that `null` is interpreted as `false` when passed as argument to
-// `caseSensitive` and `multiLine`.
-
-import 'package:expect/expect.dart';
-
-main() {
-  testCaseSensitive();
-  testMultiLine();
-}
-
-testCaseSensitive() {
-  var r1 = new RegExp('foo');
-  var r2 = new RegExp('foo', caseSensitive: true);
-  var r3 = new RegExp('foo', caseSensitive: false);
-  var r4 = new RegExp('foo', caseSensitive: null);
-  Expect.isNull(r1.firstMatch('Foo'), "r1.firstMatch('Foo')");
-  Expect.isNull(r2.firstMatch('Foo'), "r2.firstMatch('Foo')");
-  Expect.isNotNull(r3.firstMatch('Foo'), "r3.firstMatch('Foo')");
-  Expect.isNotNull(r4.firstMatch('Foo'), "r4.firstMatch('Foo')");
-}
-
-testMultiLine() {
-  var r1 = new RegExp(r'^foo$');
-  var r2 = new RegExp(r'^foo$', multiLine: true);
-  var r3 = new RegExp(r'^foo$', multiLine: false);
-  var r4 = new RegExp(r'^foo$', multiLine: null);
-  Expect.isNull(r1.firstMatch('\nfoo\n'), "r1.firstMatch('\\nfoo\\n')");
-  Expect.isNotNull(r2.firstMatch('\nfoo\n'), "r2.firstMatch('\\nfoo\\n')");
-  Expect.isNull(r3.firstMatch('\nfoo\n'), "r3.firstMatch('\\nfoo\\n')");
-  Expect.isNull(r4.firstMatch('\nfoo\n'), "r4.firstMatch('\\nfoo\\n')");
-}