Syntax highlighting for `pinned` keyword

[jnm2]

This looks sort of misleadingly like a local name rather than a keyword (link):

I suppose this would mean highlighting modreq and & too, since these are all part of the same table:

(https://www.ecma-international.org/wp-content/uploads/ECMA-335_5th_edition_december_2010.pdf page 147)

[ashmind]

Thanks for reporting! I was going to say this will take a while (until CodeMirror 6 migration is done), but IL highlighting is somewhere in my code and not in CodeMirror. So I can actually do it earlier.

It will still take a while though (OSS time) -- but less. Happy to accept a PR in the meantime.