And if it weren't for Firefox, you'd still be developing for IE6.
I'm sure that they care about those bugs, but right now the major battle for everyone is in the mobile platform area. If Firefox OS doesn't gain a foothold we're basically in walled garden area forever (even though Android is OSS I don't trust Google to not become reactionary once the market is saturated and Android dominates it; and through patents + branding Google can still prevent major forks if it wants to).
So for your own long term sake, you'd better wish that they do make it, even if they have to postpone a few CSS bug fixes.
My cringe with Firefox are misfeatures like window.onbeforeunload. They deliberately break the expected behavior due to an unreasonable decision, but no browser is perfect.
They tried a fix and it broke YouTube. So it seems like a reasonable fear. https://bugzilla.mozilla.org/show_bug.cgi?id=349259#c54
> The patch ... is literally to remove "!important" from one CSS file
It isn't a simple one line fix, as Firefox developer kindly explained. https://bugzilla.mozilla.org/show_bug.cgi?id=349259#c76
>That patch would not be welcome.
They describe what work would be required (and where the changes would likely be) for the patch to be accepted in the bug. https://bugzilla.mozilla.org/show_bug.cgi?id=349259#c80
Problem is, not everybody knows C++. Having a bug open for 7 years makes me think the issue will never be resolved. All I can do is wait or use another browser. One annoyance I have with Firefox is the lack of built in keychain support. This really summarizes how I feel: https://bugzilla.mozilla.org/show_bug.cgi?id=106400#c94
As for the original bug, this post: https://bugzilla.mozilla.org/show_bug.cgi?id=349259#c82 seems to suggest every browser but Firefox supports changing line-height. Wouldn't Firefox be going against the expected behavior?
If no one can even provide that...