Workaround for missing `prefix` in UnaryExpression generated by Esprima
Workaround for missing `prefix` in UnaryExpression generated by Esprima

See #193

eth-srl/UnuglifyJS,davidbau/UglifyJS2,sahat/UglifyJS2,avdg/UglifyJS2,supriyantomaftuh/UglifyJS2,GerHobbelt/UglifyJS2,rvanvelzen/UglifyJS2,githuboflee/first,butchi/decodecodeJS,HankMcCoy/UglifyJS2,kemitchell/UglifyJS2,TurkeyFried/uglifyjs2-dist,TrigenSoftware/ColaScript,Spocdoc/uglify-js-fork,kittens/UglifyJS2,jchbh-duplicate/UglifyJS2,beni55/UnuglifyJS,hychen/UglifyJS2,shanaithal/UglifyJS2,vjeux/UglifyJS2,VIVEKLUCKY1848/UglifyJS2,Jeremy017/UglifyJS2,hxford/UglifyJS2,microlv/UglifyJS2,shelsonjava/UglifyJS2,Venima/Test,butchi/codedecodeJS,digitalloggers/UglifyJS2,dabretin/UglifyJS2,sebmck/UglifyJS2,istr/UglifyJS2,beni55/UnuglifyJS,lautis/UglifyJS2,SpainTrain/UglifyJS2,tomByrer/UglifyJS2,sielay/UglifyJS2,eth-srl/UnuglifyJS