In a later PR, DomRoot<T> will become a type alias of Root<Dom<T>>,
where Root<T> will be able to handle all the things that need to be
rooted that have a stable traceable address that doesn't move for the
whole lifetime of the root. Stay tuned.
* Update rust-azure to 0.21.0
* Mark the following test case as fail:
tests/wpt/mozilla/tests/mozilla/css-paint-api/background-image-tiled.html
* Make the ellipse test case pass.
BUG: https://github.com/servo/servo/issues/17598
