bidi-bracket: add `None`?

[mathiasbynens]

@cscott says:

I thought about adding 'None' as a regexp, but it bloats the lookup array as a direct map. Maybe it's worth some special-casing.

[cscott]

It's also pretty heavy weight as a codepoints array and a symbol array. So it would be a weird special case that only had a regexp. Not sure it's worth it, you can always test against (!Open && !Closed) – and the Unicode folks say (in BidiBrackets.txt):

implementation can optimize the lookup of the Bidi_Paired_Bracket_Type
property values Open and Close by restricting the processing to characters
with bc=ON.

which is equivalent to our bidi/ON. (Or direct lookup in bidi/bidi/index.js.)

So I don't think it's worth the complication yet. But I'm -0 on this; I'd be interested in other opinions.

[mathiasbynens]

Okay, let’s leave it as-is for now.

Btw, @cscott, you now have commit access to this repository. Feel free to make changes, but consider working on a separate branch and submitting a pull request (for easier review) before making major changes. Thanks!