Use of Symbol breaks IE and older browser support

[onexdata]

I didn't see this issue in 4.1.1, but it looks like 4.2.0 uses Symbol, which is certainly not compatible with the older browsers listed on regexp.com (Internet Explorer 5.5+, Firefox 1.5+, Chrome, Safari 3+, and Opera 11+)

[slevithan]

xregexp.com is currently out of date and only lists pre-v4 versions at http://xregexp.com/history/. This is on me to upgrade since the documentation is not currently open source. :'( I aim to fix this but am not able to provide a timeline at this time.

XRegExp moved to only support ES5+ browsers in v4.0.0.

Looks like use of Symbol.iterator in xregexp-all.js came from @josephfrazier's 8c02a0a and is indeed new in v4.2.0. This might have been unintentional. @josephfrazier, what do you think is the best path forward for this?

[josephfrazier]

Thanks for tracking down that commit, it looks like #238 also had changes which introduced Symbol to xregexp-all.js. See #255 for a potential fix.