Fix/optimize Capture.WHICH.
Fix/optimize Capture.WHICH.

Accidentally relied on List.WHICH, even though it didn't mean to.

softmoth/rakudo,LLFourn/rakudo,b2gills/rakudo,ugexe/rakudo,ab5tract/rakudo,cognominal/rakudo,raydiak/rakudo,dankogai/rakudo,awwaiid/rakudo,nunorc/rakudo,awwaiid/rakudo,tbrowder/rakudo,skids/rakudo,nbrown/rakudo,b2gills/rakudo,sjn/rakudo,azawawi/rakudo,Gnouc/rakudo,sjn/rakudo,usev6/rakudo,lucasbuchala/rakudo,ungrim97/rakudo,skids/rakudo,samcv/rakudo,ugexe/rakudo,zostay/rakudo,paultcochrane/rakudo,LLFourn/rakudo,tony-o/rakudo,LLFourn/rakudo,skids/rakudo,ab5tract/rakudo,Gnouc/rakudo,labster/rakudo,dankogai/rakudo,samcv/rakudo,cygx/rakudo,paultcochrane/rakudo,salortiz/rakudo,ab5tract/rakudo,tbrowder/rakudo,cognominal/rakudo,cognominal/rakudo,samcv/rakudo,awwaiid/rakudo,labster/rakudo,salortiz/rakudo,MasterDuke17/rakudo,tony-o/rakudo,azawawi/rakudo,salortiz/rakudo,tony-o/rakudo,Gnouc/rakudo,salortiz/rakudo,labster/rakudo,awwaiid/rakudo,ugexe/rakudo,b2gills/rakudo,tbrowder/rakudo,nunorc/rakudo,rakudo/rakudo,Gnouc/rakudo,labster/rakudo,rakudo/rakudo,nbrown/rakudo,azawawi/rakudo,MasterDuke17/rakudo,usev6/rakudo,jonathanstowe/rakudo,ungrim97/rakudo,MasterDuke17/rakudo,cognominal/rakudo,zostay/rakudo,tbrowder/rakudo,skids/rakudo,ungrim97/rakudo,zostay/rakudo,tbrowder/rakudo,lucasbuchala/rakudo,lucasbuchala/rakudo,rakudo/rakudo,awwaiid/rakudo,softmoth/rakudo,nbrown/rakudo,rakudo/rakudo,softmoth/rakudo,rakudo/rakudo,nunorc/rakudo,sjn/rakudo,paultcochrane/rakudo,raydiak/rakudo,usev6/rakudo,sjn/rakudo,nbrown/rakudo,Gnouc/rakudo,raydiak/rakudo,jonathanstowe/rakudo,paultcochrane/rakudo,usev6/rakudo,samcv/rakudo,MasterDuke17/rakudo,tony-o/rakudo,nbrown/rakudo,zostay/rakudo,salortiz/rakudo,lucasbuchala/rakudo,cognominal/rakudo,LLFourn/rakudo,ab5tract/rakudo,tbrowder/rakudo,labster/rakudo,Gnouc/rakudo,ugexe/rakudo,MasterDuke17/rakudo,b2gills/rakudo,raydiak/rakudo,b2gills/rakudo,cygx/rakudo,ungrim97/rakudo,samcv/rakudo,nunorc/rakudo,dankogai/rakudo,nbrown/rakudo,labster/rakudo,usev6/rakudo,skids/rakudo,dankogai/rakudo,rakudo/rakudo,jonathanstowe/rakudo,ab5tract/rakudo,jonathanstowe/rakudo,softmoth/rakudo,cygx/rakudo,paultcochrane/rakudo,softmoth/rakudo,LLFourn/rakudo,ungrim97/rakudo,azawawi/rakudo,MasterDuke17/rakudo,azawawi/rakudo,ugexe/rakudo,dankogai/rakudo,tony-o/rakudo,cygx/rakudo,tony-o/rakudo,lucasbuchala/rakudo,cygx/rakudo,jonathanstowe/rakudo,salortiz/rakudo,sjn/rakudo