bug#24389: [PATCH] Support completion of classes and IDs in CSS mode

[Stefan Monnier]

> OK, I changed it to use the buffer's tick counter instead. I also
> changed `seq-uniq' to `delete-dups', which resulted in a massive
> speedup. Some benchmarks using the same test files as before follow.
[...]
> As a side note, maybe a hashing strategy like the one `delete-dups'
> uses would be good for `seq-uniq' too?

I suggest you file a separate bug report for that issue.  Maybe using
a hash table like in delete-dups will do the trick, but I suspect that
the difference between using `delete` (coded in C) vs `seq-contains`
(which additionally performs an Elisp-funcall for each element) is also
a significant factor.

The patch looks good now, thanks,


        Stefan