Fix ty::populate_implementations_for_trait_if_necessary to load the trait's impls from all the crates.

rustc: rename ty::populate_implementations_for_type_if_necessary to make it clear that it only populates inherent impls.

This syntax was removed in b24a3b82 but references remained in the
grammar, the reference, rustdoc generation, and some auxiliary test
files that don't seem to have been used since 812637e6.

Fix wrong radius valve from 0.0 to 1.0 as above

Many many many people ask in #rust about this libraries, having an
explanatory reason will probably help a lot.

If you have 0 references (`&T`) to a resource, presumably, you could
have a mutable reference (`&mut T`). So this only start to make sense
at having 1 reference to a resource.

This commit is an implementation of [RFC 1066][rfc] where the conclusion was
that leaking a value is a safe operation in Rust code, so updating the signature
of this function follows suit.

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1066-safe-mem-forget.md

Closes #25186

Perform unsafe initialization up front and then only afterward the mutex is in
place do we initialize it.

This module has been removed for quite some time!

Now that `std::old_io` has been removed for quite some time the naming real
estate here has opened up to allow these modules to move back to their proper
names.

Didn't realise 0.3.0 referred to all 0.3.x versions! Fixed my mistakes. Should have just updated the Cargo.toml now.

changed paragraphs with discussion of Cargo.lock file to agree with rand version 0.3.0 in the Cargo.tom file.

Following paragraph says "we've used `*` which..." but code says "rand=\"0.3.0\""

This style inconsistency was noted at https://travis-ci.org/rust-lang/rust/builds/61583070#L371

To separate concerns, instead of checking the state of `#toggle-all-docs` by looking at its label text, I add or remove a class `will-expand` depending on whether the button’s next click will expand everything. (The `if` statement’s two branches were swapped as part of this change.)

I moved the desired text values to a function `labelForToggleButton`, so changing the values will be easier. I also note in a comment the other file where the text is duplicated.

To allow the labels of both types of toggle buttons to be uniformly set, I added a `span.inner` to the global button too.

I split the template in `render.rs` into multiple lines to make room for the `span`, and that adds whitespace around the `[` and `]` text elements. That seems to be okay, though – the page still looks the same.

I updated the CSS styling for `.collapse-toggle > .inner` to add a little extra space around the symbol, to make minus signs easier to identify. (`#toggle-all-docs > .inner` does not need the same style, since its text size is bigger, so it naturally puts more space around the symbol.)

Closes #20626.

Closes #22463.

Closes #22258.

Closes #22037.

Closes #21701.

Closes #21562.

Closes #21177.

Nothing uses it anymore.