Optimize Hash.at_key and Hash.bind_key.
Optimize Hash.at_key and Hash.bind_key.

Gives a 14% saving on while_hash_set benchmark.

paultcochrane/rakudo,awwaiid/rakudo,rakudo/rakudo,dankogai/rakudo,tbrowder/rakudo,b2gills/rakudo,skids/rakudo,dwarring/rakudo,Gnouc/rakudo,softmoth/rakudo,nunorc/rakudo,softmoth/rakudo,cognominal/rakudo,nunorc/rakudo,salortiz/rakudo,azawawi/rakudo,samcv/rakudo,ab5tract/rakudo,awwaiid/rakudo,MasterDuke17/rakudo,paultcochrane/rakudo,niner/rakudo,tbrowder/rakudo,dankogai/rakudo,lucasbuchala/rakudo,sergot/rakudo,laben/rakudo,rakudo/rakudo,dwarring/rakudo,samcv/rakudo,zhuomingliang/rakudo,azawawi/rakudo,azawawi/rakudo,skids/rakudo,Gnouc/rakudo,ab5tract/rakudo,lucasbuchala/rakudo,labster/rakudo,zostay/rakudo,skids/rakudo,sjn/rakudo,labster/rakudo,rakudo/rakudo,b2gills/rakudo,retupmoca/rakudo,ungrim97/rakudo,cognominal/rakudo,retupmoca/rakudo,zhuomingliang/rakudo,awwaiid/rakudo,usev6/rakudo,teodozjan/rakudo,rakudo/rakudo,cygx/rakudo,cygx/rakudo,softmoth/rakudo,nbrown/rakudo,niner/rakudo,lucasbuchala/rakudo,zhuomingliang/rakudo,sergot/rakudo,tbrowder/rakudo,jonathanstowe/rakudo,usev6/rakudo,retupmoca/rakudo,ungrim97/rakudo,salortiz/rakudo,jonathanstowe/rakudo,MasterDuke17/rakudo,dankogai/rakudo,labster/rakudo,ugexe/rakudo,ungrim97/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,tony-o/deb-rakudodaily,salortiz/rakudo,Gnouc/rakudo,ab5tract/rakudo,tony-o/deb-rakudodaily,MasterDuke17/rakudo,tony-o/rakudo,rakudo/rakudo,ungrim97/rakudo,ugexe/rakudo,LLFourn/rakudo,azawawi/rakudo,skids/rakudo,Gnouc/rakudo,LLFourn/rakudo,samcv/rakudo,sjn/rakudo,cygx/rakudo,sergot/rakudo,b2gills/rakudo,tony-o/deb-rakudodaily,b2gills/rakudo,LLFourn/rakudo,tony-o/rakudo,retupmoca/rakudo,nbrown/rakudo,ugexe/rakudo,tony-o/deb-rakudodaily,cognominal/rakudo,tony-o/rakudo,cygx/rakudo,zostay/rakudo,tony-o/deb-rakudodaily,tony-o/deb-rakudodaily,niner/rakudo,ugexe/rakudo,sjn/rakudo,raydiak/rakudo,laben/rakudo,laben/rakudo,usev6/rakudo,samcv/rakudo,labster/rakudo,awwaiid/rakudo,Leont/rakudo,jonathanstowe/rakudo,paultcochrane/rakudo,samcv/rakudo,raydiak/rakudo,teodozjan/rakudo,nbrown/rakudo,LLFourn/rakudo,dankogai/rakudo,paultcochrane/rakudo,tony-o/rakudo,teodozjan/rakudo,ugexe/rakudo,nunorc/rakudo,nunorc/rakudo,dwarring/rakudo,ab5tract/rakudo,cognominal/rakudo,b2gills/rakudo,labster/rakudo,cygx/rakudo,awwaiid/rakudo,Leont/rakudo,lucasbuchala/rakudo,softmoth/rakudo,rakudo/rakudo,cognominal/rakudo,tbrowder/rakudo,LLFourn/rakudo,azawawi/rakudo,Gnouc/rakudo,jonathanstowe/rakudo,zhuomingliang/rakudo,labster/rakudo,tony-o/rakudo,softmoth/rakudo,jonathanstowe/rakudo,sergot/rakudo,tony-o/deb-rakudodaily,salortiz/rakudo,MasterDuke17/rakudo,dankogai/rakudo,tbrowder/rakudo,sjn/rakudo,skids/rakudo,salortiz/rakudo,zostay/rakudo,tony-o/rakudo,Leont/rakudo,dwarring/rakudo,nbrown/rakudo,raydiak/rakudo,nbrown/rakudo,MasterDuke17/rakudo,ungrim97/rakudo,zostay/rakudo,raydiak/rakudo,ab5tract/rakudo,nbrown/rakudo,tbrowder/rakudo,teodozjan/rakudo,usev6/rakudo,Leont/rakudo,paultcochrane/rakudo,laben/rakudo,sjn/rakudo,niner/rakudo,usev6/rakudo,salortiz/rakudo