feat(lexer): support new RegExp Indices flag "d"

[3cp]

Related to #214

[3cp]

Not behind next since it's a stage 4 feature.

[3cp]

There are lots of wrong message in this section. And there are many duplicated tests on /i/yy and /i/ss.

[3cp]

I overlooked the validation result is used.

parser.tokenValue = validate(parser, pattern, flags);

So the tokenValue is wrong for regex with 'd' flag. Not sure what's the best solution. It might need a try catch to fall back to removing "d", so that at least for Nodejs v18, the tokenValue is correct.

[aladdin-add]

a straightforward way is to do a check in the entry, something like:

var isDsupported = true;
try {new Regexp('.', 'd');}catch(e){isDsupported = false;}

we may also want to check others like /s, /u, /y...

btw, I don't think it's a good resolution to just replace them to '', as they may be misused as normal values. e.g. /./d => /./. what do you think just return an exceptional value, e.g. null?

[fisker]

Is this stored as RegExpLiteral value? It should be null per ESTree spec https://github.com/estree/estree/blob/master/es5.md#regexpliteral

[3cp]

Oh, sorry. I got it now.

[3cp]

What about

try {
  return new RegExp(pattern, flags);
} catch (e) {
  try {
    // Fallback to only validate patterns on systems 
    // where some flags are not supported.
    new RegExp(pattern);
    return null;
  } catch (e) {
    report(parser, Errors.UnterminatedRegExp);
  }
}

[aladdin-add]

it will allow unknown/dulp flags, e.g. /foo/a, /foo/gg?

[3cp]

Validation happens after the duplication check and the unknown check.