Fix #160
Fix #160

Use `font-lock-fontify-region` on the whole buffer to actually force
refontification in Emacs 24, which does not support `font-lock-ensure`.

`font-lock-fontify-buffer` is actually closer to `font-lock-flush`, so it's not
the right function to use in `rust--after-revert-hook`.

Wilfred/rust-mode,rust-lang/rust-mode,rust-lang/rust-mode