Async Pan/Zoom (APZ) lands in Firefox Quantum

Asynchronous pan and zoom (APZ) is landing in Firefox Quantum, which means jank-free, smooth scrolling for all! Until now, scrolling was part of the main JavaScript thread. This meant that when JavaScript code was being executed, the user could not scroll the page. With APZ, scrolling is decoupled from the JavaScript thread, leading to a smoother scrolling experience, especially in slower devices, like mobile phones.