Revert "[6.d] Deprecate IO::Handle.slurp-rest"
Revert "[6.d] Deprecate IO::Handle.slurp-rest"

This reverts commit 3341384bfe1341200a75ddc7ec869812cd58aeed.
https://irclog.perlgeek.de/perl6-dev/2017-09-29#i_15233995

tony-o/rakudo,awwaiid/rakudo,salortiz/rakudo,salortiz/rakudo,usev6/rakudo,jonathanstowe/rakudo,salortiz/rakudo,raydiak/rakudo,jonathanstowe/rakudo,salortiz/rakudo,rakudo/rakudo,nbrown/rakudo,tbrowder/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,softmoth/rakudo,jonathanstowe/rakudo,lucasbuchala/rakudo,softmoth/rakudo,nbrown/rakudo,awwaiid/rakudo,jonathanstowe/rakudo,awwaiid/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tony-o/rakudo,lucasbuchala/rakudo,usev6/rakudo,tbrowder/rakudo,softmoth/rakudo,labster/rakudo,rakudo/rakudo,Gnouc/rakudo,salortiz/rakudo,nbrown/rakudo,tony-o/rakudo,jonathanstowe/rakudo,Gnouc/rakudo,raydiak/rakudo,nbrown/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tony-o/rakudo,awwaiid/rakudo,rakudo/rakudo,awwaiid/rakudo,usev6/rakudo,softmoth/rakudo,tony-o/rakudo,tbrowder/rakudo,Gnouc/rakudo,raydiak/rakudo,labster/rakudo,softmoth/rakudo,lucasbuchala/rakudo,salortiz/rakudo,tony-o/rakudo,labster/rakudo,rakudo/rakudo,labster/rakudo,Gnouc/rakudo,tbrowder/rakudo,labster/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,raydiak/rakudo,nbrown/rakudo,usev6/rakudo,MasterDuke17/rakudo,usev6/rakudo,tbrowder/rakudo,labster/rakudo,rakudo/rakudo,rakudo/rakudo,nbrown/rakudo,Gnouc/rakudo,lucasbuchala/rakudo