Remove old tests that have been migrated to the v8 repo.

LayoutTests/fast/js/script-tests/regexp-look-ahead-empty.js

-description(
-'Test for regression against <a href="https://bugs.webkit.org/show_bug.cgi?id=42664">Yarr Interpreter is hanging in some cases of look-ahead regex patterns</a>.  It also tests some other related expressions.'
-);
-
-shouldBe('/(?:(?=x))+/.exec("x")', '[""]');
-shouldBe('/(?:a?)*/.exec("a")', '["a"]');
-shouldBe('/(a|ab)*/.exec("abab")', '["a","a"]');
-shouldBe('/(ab)+/.exec("abab")', '["abab","ab"]');
-// The following tests fail because of pcre interpreter bug(s).
-shouldBe('/(|ab)*/.exec("ab")', '["ab","ab"]');
-shouldBe('/(?:(|ab)*)/.exec("ab")', '["ab","ab"]');
-shouldBe('/(?:(|ab)+)/.exec("ab")', '["ab","ab"]');
-shouldBe('/(|ab)+/.exec("abab")', '["abab","ab"]');