Reapply "Port regexp tests from V8 to Dart."

tests/corelib/regexp/look-ahead_test.dart

Index: tests/corelib/regexp/look-ahead_test.dart
diff --git a/tests/corelib/regexp/look-ahead_test.dart b/tests/corelib/regexp/look-ahead_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ffb67e4515d23267d63c31e92114a9712fdf1ab9
--- /dev/null
+++ b/tests/corelib/regexp/look-ahead_test.dart
@@ -0,0 +1,35 @@
+// Copyright (c) 2014, the Dart project authors. All rights reserved.
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1.  Redistributions of source code must retain the above copyright
+//     notice, this list of conditions and the following disclaimer.
+// 2.  Redistributions in binary form must reproduce the above copyright
+//     notice, this list of conditions and the following disclaimer in the
+//     documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+// ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import 'v8_regexp_utils.dart';
+import 'package:expect/expect.dart';
+
+void main() {
+  description(
+  'Test for regression against <a href="https://bugs.webkit.org/show_bug.cgi?id=41458">Yarr Interpreter is crashing in some cases of look-ahead regex patterns</a>'
+  );
+
+  shouldBe(firstMatch("ab", new RegExp(r"a(?=b|c)")), ["a"]);
+  shouldBe(firstMatch("abd", new RegExp(r"a(?=c|b)|d")), ["a"]);
+}