…ime to prevent the style to be applied afterwards on slow connections

mark ptr-int-transmute test as no_run

This causes [CI failures in Miri](https://github.com/rust-lang/miri-test-libstd/runs/6062500259?check_suite_focus=true) since ptr-int-transmutes are rejected there (when strict provenance is enabled).

…scottmcm

Fix typo in `offset_from` documentation

Small fix for what I think is a typo in the `offset_from` documentation.

Someone reading this may understand that the distance in bytes is obtained by dividing the distance by `mem::size_of::<T>()`, but here we just want to define "units of T" in terms of bytes (i.e., units of T == bytes / `mem::size_of::<T>()`).

…r=jsha

Add rotation animation on settings button when loading

As discussed, I added an animation when the settings JS file is loading (I voluntarily made the timeout at the end of the `settings.js` super long so we can see what the animation looks like):

https://user-images.githubusercontent.com/3050060/166693243-816a08b7-5e39-4142-acd3-686ad9950d8e.mp4

r? ````@jsha````

…=compiler-errors

Add a regression test for rust-lang#64173 and rust-lang#66152

Closes rust-lang#64173
Closes rust-lang#66152

Mixed the code as the root cause seems the same.

…ding-strategy, r=jsha

Improve settings loading strategy

I learned about this thanks to ```@jsha``` who suggested this approach:

It improves the settings loading strategy by loading CSS and JS at the same time to prevent the style to be applied afterwards on slow connections.

r? ```@jsha```

Implement [OsStr]::join

Implements join for `OsStr` and `OsString` slices:

```Rust
    let strings = [OsStr::new("hello"), OsStr::new("dear"), OsStr::new("world")];
    assert_eq!("hello dear world", strings.join(OsStr::new(" ")));
````

This saves one from converting to strings and back, or from implementing it manually.

…, r=compiler-errors

Add `track_caller` to `DefId::expect_local()`

Suggested in rust-lang#96738 (comment).
`DefId::expect_local()` often causes ICEs (panics) and should be a good candidate to add `track_caller`.