Add more tests for v flag

[sosukesuzuki]

The behavior of the following built-ins and abstract operations depends on the v flag.

• RegExp.prototype.@@match
• RegExp.prototype.@@matchAll
• RegExp.prototype.@@replace
• RegExp.prototype.@@search
• RegExpBuiltinExec

The unicode mode is enabled by the step such as

If flags contains "u" or flags contains "v", let fullUnicode be true.

There is a test in test262 for using these built-ins with the u flag(¹), but not for the v flag.

So we had a bug² in WebKit where RegExp.prototype.@@matchAll did not support the v flag (already fixed).

We should add tests for this in test262.

Footnotes

1. https://github.com/tc39/test262/blob/main/test/built-ins/RegExp/prototype/Symbol.match/u-advance-after-empty.js ↩

2. https://bugs.webkit.org/show_bug.cgi?id=272274 ↩