I think bugzilla, mailinglists and irc channels might be better places to request a feature request than a comment on hacker news.

I got no clue how to get to Bugzilla. I made other bug request, but I have no idea where those went (It was one of those Feedback sites for Mozilla with I have an idea, etc.)

If you made the suggestion through a feedback mechanism, it goes into a big database along with the millions of other feedback entries. The support team at Mozilla is responsible for combing through that database looking for common themes and especially for trending issues.

I'd guess your request probably isn't very common, so you probably wouldn't get the same potential attention that you would get if you were to go to bugzilla.mozilla.org and file a bug there.

Mozilla's bug tracker is at https://bugzilla.mozilla.org/

perhaps, so long as it's not a request for WebP support

Should be pretty easy to add that functionality! File a bug on https://bugzilla.mozilla.org. In fact, this would make a great first bug for a new contributor :)