Support d flag

[RebeccaStevens]

Any regex using the d flag is reported.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions#advanced_searching_with_flags

Ideally, this should be fixed in the upstream, but as the d flag doesn't really change how the regex executes, a workaround could be to simply remove the d flag before passing to the optimize library.