support old browsers

[mindhacker0]

the packed files seems has es6+ features，it did not work on old browsers.is there some way to make babel/preset-env plugin work on output files

[nikkorn]

Hiya, which browser/version did you have in mind?

[mindhacker0]

@nikkorn thanks for reply,i need to compatible with QT 5.15.2 which chromium version is 69.0.3497.128,the optional chain syntax throw errors,would you like pack legacy-esmjs in ouput files,so i can replace files in resolve.alias