> their embedded JS (ES3?) engine Your wish has already been granted. "Source code for the Actionscript virtual machine": https://github.com/adobe-flash/avmplu

> their embedded JS (ES3?) engine Your wish has already been granted. "Source code for the Actionscript virtual machine": https://github.com/adobe-flash/avmplus https://github.com/adobe-flash/avmplus 4 years old, dunno how closely it tracks the current Actionscript interpreter in the Flash plugin. It's also worth noting that they donated this VM to Mozilla eleven years ago, according to Wikipedia: https://en.wikipedia.org/wiki/Tamarin_(software) https://en.wikipedia.org/wiki/Tamarin_(software)