rustc_resolve: never push `ClosureRibKind` to `label_ribs`.
rustc_resolve: never push `ClosureRibKind` to `label_ribs`.

graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust