auto merge of #11672 : bjz/rust/remove-times, r=brson

`Times::times` was always a second-class loop because it did not support the `break` and `continue` operations. Its playful appeal (which I liked) was then lost after `do` was disabled for closures. It's time to let this one go.

diff --cc src/etc/vim/syntax/rust.vim
Simple merge

diff --cc src/libstd/prelude.rs
Simple merge