Reporting lookahead not supported in IOS

[latel]

It's seems lookahead and negative lookahead is well supported in all browsers, see documents below:

• https://caniuse.com/?search=js-regexp-lookahead
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Lookahead_assertion

[dasa]

I think this may get fixed by PR #6