bug#19397: incorrect handling of / in a character class in js-mode

[Stefan Monnier]

> Try to type the following code in a JS buffer:
> function test ()
> {
>     return /[/]/.test ('/')
> }

Indeed, there are two problems here: js-mode treats the first / as
a division operation, and even if you change the code to avoid this
problem, you bump into the fact that js-mode doesn't know there can be
"unescaped / in character class".

I installed a fix for the first problem into emacs-24.
For the second problem, I recommend you escape the slash for now (IIUC
the syntax of regexps in ecmascript, that will DTRT).


        Stefan