Check if `t.is` is already defined (specifically accounting for the isImmutable method in validators
Check if `t.is` is already defined (specifically accounting for the isImmutable method in validators

kellyselden/babel,Skillupco/babel,KunGha/babel,shuhei/babel,chicoxyzzy/babel,chicoxyzzy/babel,hzoo/babel,antn/babel,PolymerLabs/babel,iamchenxin/babel,claudiopro/babel,kaicataldo/babel,zjmiller/babel,samwgoldman/babel,zertosh/babel,garyjN7/babel,garyjN7/babel,guybedford/babel,maurobringolf/babel,STRML/babel,hulkish/babel,hulkish/babel,claudiopro/babel,samwgoldman/babel,hzoo/babel,lxe/babel,guybedford/babel,chicoxyzzy/babel,jridgewell/babel,iamchenxin/babel,jridgewell/babel,kellyselden/babel,kedromelon/babel,kellyselden/babel,babel/babel,existentialism/babel,tikotzky/babel,bcoe/babel,iamchenxin/babel,shuhei/babel,kellyselden/babel,kassens/babel,jchip/babel,babel/babel,PolymerLabs/babel,zertosh/babel,kaicataldo/babel,claudiopro/babel,vadzim/babel,Skillupco/babel,PolymerLabs/babel,kedromelon/babel,Skillupco/babel,existentialism/babel,ccschneidr/babel,existentialism/babel,bcoe/babel,lxe/babel,babel/babel,Skillupco/babel,ccschneidr/babel,jchip/babel,KunGha/babel,kaicataldo/babel,jridgewell/babel,hulkish/babel,shuhei/babel,babel/babel,rmacklin/babel,vadzim/babel,samwgoldman/babel,rmacklin/babel,kedromelon/babel,STRML/babel,tikotzky/babel,guybedford/babel,hulkish/babel,maurobringolf/babel,hzoo/babel,antn/babel,kassens/babel,maurobringolf/babel,zjmiller/babel,hzoo/babel,chicoxyzzy/babel,jridgewell/babel,kaicataldo/babel