Upgrade Regenerator to v0.8.39
Upgrade Regenerator to v0.8.39

Most notably, this release fixes a bug that made it difficult for Promise implementations to track unhandled rejections when using async functions: https://github.com/facebook/regenerator/commit/3d8ee21f3ae918edcc04b8b18b0b5f7208883bf0
cgvarela/babel,hzoo/babel,PolymerLabs/babel,framewr/babel,sejoker/babel,cartermarino/babel,mrapogee/babel,garyjN7/babel,PolymerLabs/babel,ajcrites/babybel,drieks/babel,kellyselden/babel,kpdecker/babel,maurobringolf/babel,Industrial/babel,samwgoldman/babel,rmacklin/babel,michaelficarra/babel,chicoxyzzy/babel,maurobringolf/babel,ccschneidr/babel,hulkish/babel,framewr/babel,vadzim/babel,mgcrea/babel,zenlambda/babel,zjmiller/babel,zjmiller/babel,sejoker/babel,existentialism/babel,claudiopro/babel,guybedford/babel,douglasduteil/babel,kedromelon/babel,shuhei/babel,jchip/babel,abdulsam/babel,mrtrizer/babel,CrocoDillon/babel,fabiomcosta/babel,cgvarela/babel,sejoker/babel,codenamejason/babel,garyjN7/babel,jeffmo/babel,dekelcohen/babel,babel/babel,tikotzky/babel,forivall/babel,Mark-Simulacrum/babel,kellyselden/babel,AgentME/babel,zenparsing/babel,jridgewell/babel,vhf/babel,CrocoDillon/babel,mgcrea/babel,jhen0409/babel,jhen0409/babel,vhf/babel,iamstarkov/babel,iamchenxin/babel,guybedford/babel,james4388/babel,koistya/babel,chicoxyzzy/babel,kaicataldo/babel,zenparsing/babel,hulkish/babel,KualiCo/babel,hulkish/babel,vadzim/babel,zertosh/babel,kedromelon/babel,kellyselden/babel,PolymerLabs/babel,chicoxyzzy/babel,michaelficarra/babel,Skillupco/babel,KualiCo/babel,iamchenxin/babel,benjamn/babel,inikulin/babel,cartermarino/babel,iamstarkov/babel,cgvarela/babel,inikulin/babel,jchip/babel,KunGha/babel,moander/babel,antn/babel,bcoe/babel,iamchenxin/babel,tikotzky/babel,krasimir/babel,kpdecker/babel,forivall/babel,KunGha/babel,douglasduteil/babel,moander/babel,Industrial/babel,koistya/babel,Skillupco/babel,benjamn/babel,lxe/babel,claudiopro/babel,Mark-Simulacrum/babel,Skillupco/babel,drieks/babel,inikulin/babel,abdulsam/babel,Victorystick/babel,jeffmo/babel,mrtrizer/babel,STRML/babel,rmacklin/babel,ameyms/babel,jridgewell/babel,Mark-Simulacrum/babel,fabiomcosta/babel,hulkish/babel,kaicataldo/babel,lxe/babel,james4388/babel,mrapogee/babel,douglasduteil/babel,existentialism/babel,mrapogee/babel,james4388/babel,ameyms/babel,shuhei/babel,babel/babel,kellyselden/babel,krasimir/babel,Skillupco/babel,Victorystick/babel,dustyjewett/babel-plugin-transform-es2015-modules-commonjs-ember,cartermarino/babel,babel/babel,kaicataldo/babel,moander/babel,STRML/babel,jridgewell/babel,antn/babel,hzoo/babel,DmitrySoshnikov/babel,ajcrites/babybel,claudiopro/babel,framewr/babel,kaicataldo/babel,babel/babel,michaelficarra/babel,mcanthony/babel,mcanthony/babel,ajcrites/babybel,jeffmo/babel,abdulsam/babel,hzoo/babel,Victorystick/babel,bcoe/babel,maurobringolf/babel,existentialism/babel,guybedford/babel,codenamejason/babel,samwgoldman/babel,DmitrySoshnikov/babel,koistya/babel,zertosh/babel,AgentME/babel,codenamejason/babel,hzoo/babel,kassens/babel,shuhei/babel,forivall/babel,kedromelon/babel,jridgewell/babel,drieks/babel,kassens/babel,dekelcohen/babel,mcanthony/babel,mgcrea/babel,ccschneidr/babel,chicoxyzzy/babel,zenlambda/babel,KualiCo/babel,samwgoldman/babel,zenlambda/babel