Since rust-lang#72889, the Rust wasm target doesn't use --passive-segments, so
remove the `--export=__wasm_init_memory`.

As documented in the [tool-conventions Linking convention],
`__wasm_init_memory` is not intended to be exported.

[tool-conventions Linking convention]: https://github.com/WebAssembly/tool-conventions/blob/7c064f304858f67ebf22964a84b7e9658e29557a/Linking.md#shared-memory-and-passive-segments

Fix rust-lang#102057.

Fixes a regression caused by 8846c08, where
a header's top margin used to be collapsed, but isn't any more.

This line was added in c494a06, because at
the time, the headers had these classes on them. Now, the headers are
children of the `<section>` with the class on it.

This commit also adds a test case, to make sure the srclink font weight does
not regress again.

More cleanup for 8846c08, this time in trait
layouts when things are collapsed.

…=cjgillot

Fix span of byte-escaped left format args brace

Fix rust-lang#102057 (see issue for example).

Previously, the use of escaped left braces (`\x7B`) in format args resulted in an incorrectly offset span. This patch fixes that by considering any escaped characters within the string instead of using a constant offset.

…it-memory, r=nagisa

Don't export `__wasm_init_memory` on WebAssembly.

Since rust-lang#72889, the Rust wasm target doesn't use --passive-segments, so remove the `--export=__wasm_init_memory`.

As documented in the [tool-conventions Linking convention], `__wasm_init_memory` is not intended to be exported.

[tool-conventions Linking convention]: https://github.com/WebAssembly/tool-conventions/blob/7c064f304858f67ebf22964a84b7e9658e29557a/Linking.md#shared-memory-and-passive-segments

… r=jsha

rustdoc: cut margin-top from first header in docblock

Fixes a regression caused by 8846c08, where a header's top margin used to be collapsed, but isn't any more.

## Before

![image](https://user-images.githubusercontent.com/1593513/192893092-8e158bf7-ae18-41ef-8f11-6f34c724d345.png)

## After

![image](https://user-images.githubusercontent.com/1593513/192893139-d6ee06bf-9c0b-4194-bd5d-636312c89367.png)

… r=GuillaumeGomez

rustdoc: remove bad CSS font-weight on `.impl`, `.method`, etc

This line was added in c494a06, because at the time, the headers had these classes on them. Now, the headers are children of the `<section>` with the class on it.

This commit also adds a test case, to make sure the srclink font weight does not regress again.

… r=jsha

rustdoc: add method spacing to trait methods

More cleanup for 8846c08, this time in trait layouts when things are collapsed.

This PR makes two changes to the appearance of trait pages:

* It adds the `method-toggle` class to method toggles on traits, making the DOM more consistent with type pages (which already have this class).

  ## Before

  ![image](https://user-images.githubusercontent.com/1593513/192914353-ed17e1eb-df1d-480b-9998-3b5e8283b0ee.png)

  ## After

  ![image](https://user-images.githubusercontent.com/1593513/192914570-bdd0f2e1-5254-4e2e-9576-a797b82b3b3b.png)

* It adds a bottom margin to docblocks nested directly in the implementors list, giving it a similar appearance to if it was nested within a toggle.

  ## Before

  ![image](https://user-images.githubusercontent.com/1593513/192914503-1c3f39d5-690f-44ec-8f11-385302477d04.png)

  ## After

  ![image](https://user-images.githubusercontent.com/1593513/192914702-cbce4b3b-5cc6-49dc-b7f8-73be9e76791c.png)

tidy: make rustc dependency error less confusing

The current wording leads to very confusing messages:
```
tidy error: Dependencies for main workspace not explicitly permitted:
* unicode-ident 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)
```
Miri is part of that workspace, and there never was a problem adding Miri dependencies. The actual error is that due to a crate bump this now showed up as a rustc dependency, and *those* are restricted.

Split out the error reporting logic into a separate function

I was trying to read the function and got distracted by the huge block of code in the middle of it. Turns out it only reports diagnostics and all paths within it end in an error. The main function is now more readable imo.