The URL spec recently changed and the variour "mixins" interfaces are gone,
this commit updates our code and WPT accordingly.
The new expected failures related to HTMLAnchorElement and HTMLAreaElement's
attributes are due to their moving to the HTMLHyperLinkElementUtils interface,
which is not anymore in a separate `<script class=untested>` element.
Source-Repo: https://github.com/servo/servo
Source-Revision: f73cd40282ab79f53b38f2b057677b0423282f32
Extracted this out of #5649
This commit was created with the following commands:
```
find . -iname "*.webidl" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
```
find . -iname "*.rs" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```
Source-Repo: https://github.com/servo/servo
Source-Revision: 4997d3a112354a407365fede1ab1944834a2e13c
