Eliminate regenerator from preset-react-app plugins (#4630)
Eliminate regenerator from preset-react-app plugins (#4630)

Regenerator is already included by preset-env.

Fixes #4627
timlogemann/create-react-app,mangomint/create-react-app,ConnectedHomes/create-react-web-app,d3ce1t/create-react-app,IamJoseph/create-react-app,jdcrensh/create-react-app,jdcrensh/create-react-app,d3ce1t/create-react-app,infernojs/create-inferno-app,infernojs/create-inferno-app,d3ce1t/create-react-app,facebookincubator/create-react-app,Timer/create-react-app,ConnectedHomes/create-react-web-app,timlogemann/create-react-app,viankakrisna/create-react-app,mangomint/create-react-app,facebookincubator/create-react-app,GreenGremlin/create-react-app,viankakrisna/create-react-app,d3ce1t/create-react-app,jdcrensh/create-react-app,Timer/create-react-app,Timer/create-react-app,facebookincubator/create-react-app,jdcrensh/create-react-app,Timer/create-react-app,GreenGremlin/create-react-app,timlogemann/create-react-app,ConnectedHomes/create-react-web-app,IamJoseph/create-react-app,GreenGremlin/create-react-app,GreenGremlin/create-react-app,mangomint/create-react-app,viankakrisna/create-react-app,IamJoseph/create-react-app,timlogemann/create-react-app,ConnectedHomes/create-react-web-app,mangomint/create-react-app,infernojs/create-inferno-app