Update regexpu’s API following the breaking regexpu-core changes in #49

[mathiasbynens]

https://github.com/mathiasbynens/regexpu#regexputranspilecodecode-options

#49 changed regexpu-core’s API. We should make sure that these changes are reflected in the upstream regexpu project as well, e.g. in regexpu.transpileCode(code, options).

cc @nicolo-ribaudo