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
Fixes#5460. This supports for simple focusable elements that are their own DOM anchors, like text `input` fields.
Requires servo/rust-selectors#20. r? @SimonSapin
Source-Repo: https://github.com/servo/servo
Source-Revision: b63fb0c0a7e9cd9208d66319c910750aaaac844c
This does not implement any notion of CSSStyleDeclaration objects that do not have an owning element; there's no actual CSS object model in play here. This does support setting and getting properties of the style attribute for HTMLElement, and tries to implement the ambiguous CSS value serialization spec.
Source-Repo: https://github.com/servo/servo
Source-Revision: 824788649cd338c044d9396166af5b0f378d6685
Still need to impl `Activatable` on all activatable elements. I'll probably push those changes to this PR, however they can be made separately as well.
Source-Repo: https://github.com/servo/servo
Source-Revision: 19c69b1625dda46d3c5501292e7e2d0328e400b4
