Fix non ES5 compliant regexp

[zetaben]

ES5 appears to require that { be escaped when not used as part of a quantifier. While this works fine in browsers, it appears to choke less lenient runtimes (e.g. Duktape).

A similar case is discussed in Duktape (svaarala/duktape#69 and svaarala/duktape#74).

Please find attached a simple Duktape-powered C file that tries to parse the given argument file.
test.c.zip

Compile and run using:

$  gcc -std=c99 -o test test.c duktape-1.3.1/src/duktape.c -I duktape-1.3.1/src/  -lm && ./test chai/chai.js

When choking it produces a:
eval failed: SyntaxError: invalid regexp quantifier (unknown char) (line 4401)
when the parsing is fine it will produce :
result is: undefined

[keithamus]

Good catch @zetaben. Normally I'd ask for some tests but I'm not exactly how you could test this one without adding something like Duktape to our test suite!

[zetaben]

Thanks @keithamus !

As for tests, I was also not sure of what could be done, maybe a script that depend on execjs (https://github.com/rails/execjs) or duktape.rb (https://github.com/judofyr/duktape.rb) could be launched by your travis ? It would enable to check correct parsing under a few JS runtime without directly depending on them in the project.