Extracted out of #5649
* add more hyperlinks to associated specification for structs/methods
* follow redirects and update links
* replace broken links
* removal of WHATWG multipage page name since the page name is not
guaranteed to be stable
Source-Repo: https://github.com/servo/servo
Source-Revision: 3dc25af9e121db010e4385efb3863ba45b0e0bcf
For the majority of these cases, `as_slice` can be removed due to
`Deref`. In particular, `Deref` for:
* `String` -> `str`
* `Atom` -> `str`
The latter of those two requires, a bump of the locked `string-cache`
library
Source-Repo: https://github.com/servo/servo
Source-Revision: 0fd41847a39be387c03bd5d8b6f2aec2b1bb6f66
