Background images are loading as fully white images in Firefox 59

For example, this is the background image URL for #winamp2-js .playlist-top-left-fill in Firefox:

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABkAAAAUCAYAAAB4d5a9AAAAH0lEQVQ4jWP4TwfAMGrJqCWjloxaMmrJqCWjltDbEgCh38iahkvgggAAAABJRU5ErkJggg==

but the following is the URL when loaded in Chrome:

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABkAAAAUCAYAAAB4d5a9AAAAWUlEQVRIS2PU1nL+z0BjwFhRPoH2ltjZJAwTS+TllWjvk7ZyX9pb0jeRDhFvYqBDe5+kxzjR3hK6xImKqibtfUKXzEiXsosulowWkKRUQYx0SV10sYQeqQsAf0Ul/5LwY0QAAAAASUVORK5CYII=

[captbaritone]

I wonder if it’s some special setting?

I’m going to close this, since nobody else has been able to reproduce it, but I’ll keep my eye open for other people seeing things like this. Thanks for reporting!

[Nightfirecat]

I’m able to produce good behavior when using a clean profile, but I couldn’t find any logs that seemed helpful…

When loading in my current profile, the following logs are generated:

Content Security Policy: The report URI (about:blank) should be an HTTP or HTTPS URI.
Content Security Policy: The page’s settings observed the loading of a resource at https://webamp.org/service-worker.js (“worker-src”). A CSP report is being sent.
Service worker event waitUntil() was passed a promise that rejected with 'TypeError: Cache got basic response with bad status 206 while trying to add request https://webamp.org/mp3/llama-2.91-deed9f60e1c2a04e753d90c72d57bea1.mp3'.
workbox-core.prod.js:1:2505

When loading with add-ons disabled (still bad behavior), or from a fresh profile (good behavior), only the last line is logged:

Service worker event waitUntil() was passed a promise that rejected with 'TypeError: Cache got basic response with bad status 206 while trying to add request https://webamp.org/mp3/llama-2.91-deed9f60e1c2a04e753d90c72d57bea1.mp3'.
workbox-core.prod.js:1:2505