This is a start towards fixing #3868. Not all callers have been fixed yet, so the `Deref` implementation remains for now.
Source-Repo: https://github.com/servo/servo
Source-Revision: 141b5d038fad3c0c44a6f1b309b8ca9edea54580
`str::to_string()` goes through a `Formatter`, `str::into_string()` is a direct copy and is apparently 5× faster.
This is a rebase of the boring and bitrot-prone parts of #4366.
Source-Repo: https://github.com/servo/servo
Source-Revision: 9857ea26cb9ee262654bee97322dbbf373486bff
Still need to impl `Activatable` on all activatable elements. I'll probably push those changes to this PR, however they can be made separately as well.
Source-Repo: https://github.com/servo/servo
Source-Revision: 19c69b1625dda46d3c5501292e7e2d0328e400b4