OK smart boy. The mozilla project is open source. If this bug is so all-fired important to you, get to coding, or because you admit you don't have the skills, hire someone who can code it. Don't go whining "THEY won't fix a bug I care about". This 'bug' isn't going to get fixed simply because the folks who could fix it have far better things to spend time on than working around an arbitrary limitation in a not-too-far-in-the-future legacy 32-bit platform. I would be willing to wager that your assertion that web pages have lots of GIFs any more is false anyway. The PNG and JPG formats have pretty much completely replaced that 80s-era 256-color format.
As a matter of fact, with the introduction of things like infallible malloc, you're likely to see more badly-engineered platforms crashing on crappy web pages.
But again I say, if YOU don't like the bug, then YOU fix it, and submit a patch. If they don't accept your patch, then you can build your own FF from source and patch it however crazy way you want.
And by the way, the wikipedia page on GIF, http://en.wikipedia.org/wiki/Graphics_Interchange_Format, doesn't crash FF 3.6.10 running on OS X Snow Leopard in 32-bit mode. As they say in the business, WORKSFORME.