Yay, I now have bragging rights for "I have a commit in #Firefox" I fixed a regression with frame animation waiting in the #webdriver #BiDi code. Many thanks to the super helpful and friendly Firefox #developers, Julian and Henrik!
https://hg-edge.mozilla.org/integration/autoland/rev/89213e1b63b61ae3c8e679d689c409ebe1f409d7
(plus the parent commit with some preparatory code refactoring)