Support ES6 Unicode escaped identifiers

[getify]

The new Unicode "code point escape" form is also valid for identifiers, such as:

var \u{2B400} = 42;

AFAICT, no one has implemented this part of the grammar yet. As usual, @mathiasbynens has a bunch of great stuff about what makes a valid Unicode identifier in ES6 vs ES5, etc.

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BTW:

I'm not sure, but support of this feature may just need to be that such variables are straight up hygenically renamed to something else entirely, because there's (AFAICT) no equivalent way to do those kind of identifier names in pre-ES6.

[sebmck]

Please request this upstream at acorn.

[getify]

acornjs/acorn#214

[mathiasbynens]

acornjs/acorn#214 and acornjs/acorn#215 are now fixed.

[sebmck]

Will take a little longer than I hoped since acorn is radically changing it's structure and will require me to rewrite all the custom acorn extensions (ES7, Flow etc). Once acornjs/acorn#216 is merged I should be able to nut through it in a day.

[sebmck]

Fixed in the experimental branch.

[getify]

is this going to stay only in "experimental" mode?

[sebmck]

No, the experimental branch is the current unstable branch (terrible name I know).

[getify]

ahh, ok, sorry for misunderstanding. thanks! :)