With Firefox's move to the new Chrome-inspired extensions framework, I hope it's able to provide the required hooks to implement a capable ad blocker. That is, if you compare what ads get through uBlock Origin in Chrome vs uBlock Origin in Firefox, it's clear that the Firefox version is able to hook into events that for example block images that are loaded by the 1st party javascript as base64 data uris. These images are never blocked in chrome based browsers.