rustdoc: add [src] links to associated functions inside an impl block
While impl blocks currently have a `[src]` link to show the source for the impl block as a whole, individual methods inside that impl block do not. This can pose a problem for structs with a lot of methods, like many in libstd. This change adds little `[src]` links to individual methods that point directly to the function in the bundled source.
fixes#12932

Previously, the union fields would all render on the same line with
hideous spacing; comparison to the analogous section for structs makes
it undoubtable that `display: block` is the true intent.
Concisely and definitively resolves#43404 and its perfidious
malignancy.
rustdoc: Fix implementors list javascript
* Use a different loop variable, `i` was already taken. This caused
missing items in the implementors list.
* Use `.getAttribute('href')` rather than `.href` to get the relative
URL which is what it needs to actually fix the links.
More fallout from #41307.
r? @GuillaumeGomez
* Use a different loop variable, `i` was already taken. This caused
missing items in the implementors list.
* Use `.getAttribute('href')` rather than `.href` to get the relative
URL which is what it needs to actually fix the links.
Makes the sidebar a light grey and highlights the currently viewed item
in the sidebar more prominently.
All visual design credit goes to @johnwhelchel (#37856)
rustdoc: add line breaks to where clauses a la rustfmt
Much like my last PR for rustdoc (#36679), this adds line breaks to certain statements based on their line length. Here the focus was on where clauses.
Some examples:
- [Where clause in a trait function](https://shiva.icesoldier.me/custom-std/std/iter/trait.Iterator.html?search=#method.unzip) (also in the trait header block at the top of the page)
- [Where clause on a bare function](https://shiva.icesoldier.me/doc-custom2/petgraph/visit/fn.depth_first_search.html)
- [Where clauses in trait impls on a struct](https://shiva.icesoldier.me/custom-std/std/collections/struct.HashMap.html) (scroll to the bottom) These are regularly not on their own line, but will be given their own line now if their "prefix text" doesn't give them enough room to sensibly print their constraints. HashMap's trait impls provide some examples of both behaviors.
The libstd links above are the whole docs rendered with this, and the "bare function" link above is in another set that pulls some notable crates together. `petgraph` was the one that brought this request up, and that collection also includes [itertools](https://shiva.icesoldier.me/doc-custom2/itertools/trait.Itertools.html) which provided an easy sample to test with.
r? @GuillaumeGomez