Rollup merge of rust-lang#104129 - notriddle:notriddle/102576-js-notable-trait, r=Manishearth

rustdoc: use javascript to layout notable traits popups

Fixes rust-lang#102576

Preview: https://notriddle.com/notriddle-rustdoc-demos/102576-js-notable-trait/std/iter/trait.Iterator.html#method.step_by

## Before

![image](https://user-images.githubusercontent.com/1593513/200432713-23aa8d49-ba2b-469f-9eab-089e0c174039.png)

## After

![image](https://user-images.githubusercontent.com/1593513/200432735-edd5b53d-e99d-4fc5-9410-8a79e0efdc9d.png)

Author: Manishearth