Yesterday it was brought up that KDE support has been dropped from the Firefox package, so the firefox-kde-support will be stripped from Precise (12.04). This is becoming because the Ubuntu Firefox maintainer no longer wants to maintain the KDE support patch, which isn't mainline in Firefox.
The stock Firefox web-browser could be used instead, but it will be without any KDE integration support. This "KDE support" is about using KDE file dialogs, file associations, protocol handlers, and other features that up to this point have been better integrated with the KDE desktop.
Below is the relevant portion of a Kubuntu IRC discussion from yesterday discussing the removal of KDE Firefox support from K/Ubuntu 12.04.
[14:13] [MountainX] where should I discuss Firefox-related KDE integration issues? The package firefox-kde-support appears to be broken for 12.04. https://bugs.launchpad.net/ubuntu/+source/kmozillahelper/+bug/949949
[14:13] [ubottu] Launchpad bug 949949 in kmozillahelper (Ubuntu) "KDE support for firefox doesn't work" [Undecided,Confirmed]
[14:13] [Riddell] MountainX: debfx knows his stuff on that
[14:16] [Whois] debfx is ~firstname.lastname@example.org (Felix Geyer)
[14:16] [Whois] debfx is a user on channels: #kubuntu-devel
[14:21] [debfx] MountainX: kde support has been dropped in the firefox package so we'll remove firefox-kde-support from precise.
[14:24] [MountainX] debfx: wow, that's very bad news for Kubuntu :(
[14:25] [MountainX] debfx: do you have a link or reference for the backstory on this decision? What or who brought this about?
[14:27] [debfx] MountainX: the ubuntu firefox maintainer is no longer willing to maintain the patch (it has no chance of being accepted upstream)
[14:29] [MountainX] am I over reacting or is there a trend developing recently that looks bad for Kubuntu?
[14:30] [micahg] debfx: I assume that you or someone else have tried to figure out what it would take to upstream this support?
[14:39] [debfx] micahg: the kde integration was not written with the intention to upstream it
[14:40] [debfx] MountainX: the real problem is that mozilla doesn't care much about kde and no one from the community stepped up to write the necessary code for a proper kde integration.
[14:45] [Riddell] MountainX: you're over reacting
[14:45] [Riddell] debfx: do you know what suse do now for firefox kde integration?
[14:46] [debfx] Riddell: they still maintain the patch in their package
[14:54] [MountainX] Riddell: Yes, maybe I'm over reacting. But I'm in the midst of making a decision between opensuse and Kubuntu, and I just decided to go with Kubuntu. So this news (and Canonical's recent news) seemingly has a significant impact on me.
[14:54] [MountainX] I plan to invest the time to get deeply familiar with one distro, so I'm making a long term commitment. Really good GTK intregration is an important feature of a KDE distro to me.
[14:57] [tsimpson] the news from Canonical has no real effect on you, unless you wanted to buy commercial support
[14:57] [tsimpson] as for FF, the KDE support was always really just a hack, and that's just not good in production systems
[14:58] [tsimpson] there's nothing really wrong with just running the stock firefox if you want to use it, or any of the other browsers in the repositories
[14:58] [MountainX] yes, I do pay for a support contract and it is up for renewal in a couple weeks
[14:59] [MountainX] tsimpson: nothing wrong with it in Kubuntu unless you've used opensuse and gotten spoiled by the beautiful integration. ;)
[15:00] [debfx] tsimpson: the kde integration is a hack but that doesn't mean it's unstable, only that it's difficult to maintain.
[15:00] [tsimpson] if the patch is unmaintained, then it's not really justifiable to include it though
[15:00] [tsimpson] debfx: I didn't mean it was unstable, just not a chance it was ever going to be integrated