Shared components used by Firefox and other Mozilla software, including handling of Web content; Gecko, HTML, CSS, layout, DOM, scripts, images, networking, etc. Issues with web page layout probably go here, while Firefox user interface issues belong in the Firefox product. (More info)
On Android XUL, reftests/svg/image/image-opacity-01.svg fails due to slight color difference when SVG display lists are enabled. I'm just going to mark it as fuzzy. Since Android XUL is going to die, it's not worth figuring out and fixing really.