Re: FFS FF
I'm not currently having problems with Google Maps on Firefox so it's probably one of those "random things that break" when you upgrade and, unfortunately, will be peculiar to your own set up.
A few months ago I had something similar. When zooming in on a Google Map, it would completely flip the entire map on it's head so that the map, all text and even any map markers were upside down (not rotated but mirrored, so even standing on my head to view it wouldn't have been worthwhile). Starting Firefox with add-ons disabled stopped it from happening but disabling the add-ons manually didn't! I couldn't find any reference to other people having the same problem so, in the end, I completely wiped and re-installed Firefox (after saving the passwords and bookmarks files, hoping they weren't the problem - they weren't).
Now, I'm finding that when the latest version Chrome starts up it is refusing to show my home page (even though it is plainly set up properly in the settings). Oh well, another wipe and reinstall will probably cure it, sigh...