Rollup merge of #140314 - lolbinarycat:rustdoc-js-scrape-examples-typecheck, r=notriddle

Rustdoc: typecheck scrape-examples.js

more typechecking progress, this time we're mostly held back by the fact that `document.querySelectorAll` can't return nice types if its given a compound query (see the issue linked in a code comment).

Additionally, it seems like the generated `data-locs` attribute has fields that are never used by anything?

r? ```@notriddle```

Author: jhpratt