Created attachment 730549 [details] Fix. The interface nsIDOMMimeType is going away as part of my work to convert navigator.plugins and navigator.mimeTypes (in bug 855611). We can instead just expose arrays of mime types, descriptions, and suffixes, which is all I believe the current consumers care about (all of 2 of them in the tree AFAICT). Cc:ing dolske and fryn who exposed this code (in bug 747300). This is currently on try at https://tbpl.mozilla.org/?tree=Try&rev=194a84bc47b2
Created attachment 730550 [details] [diff] [review] Fix.
Try run is all green.