bug#25529: diagnosis and one approach to a fix

[Dmitry Gutov]

Hey Tom,

On 05.02.2017 20:43, Tom Tromey wrote:
> Tom> Another way is to use a regexp, see appended.
> Tom> I'll try to write a test for this soon.
>
> Now with a test.

This is very good, thank you. Here's just one example I've come so far 
that works with the old code, but not with yours:

let x = /[/]/;

And that's probably just because the new js-syntax-propertize-regexp 
doesn't move point forward after matching (the current one leaves it 
after the closing slash), because the regexp in js-syntax-propertize is 
too primitive.

We could try to combine the regexps together, though. Then we'd move the 
syntax-ppss status check inside the rule for the opening delimiter, and 
use a simple one for the closer.

> +  "Regular expression matching the body of a JavaScript regexp literal.")

Maybe remove "the body of". The regexp matches the delimiters as well.

Thanks!