Who wants to compile webkit and doesn't have a 64-bit machine? Seriously, my phone is 64-bit. The only 32-bit computer in my house surprised me by showing up on my LAN once. I hadn't realized it was still plugged in to power and ethernet.
Any decent development machine nowadays is 64-bit with plenty of memory to compile webkit (RAM is cheap). You can use 32-bit bearskins and stone knives if you want, and they're just fine for a whole lot of things, but not for serious development.
Sure, you can do object-oriented C. I've done it. It includes extra stuff that you have to remember to write, and which is something you can get wrong. C++ classes are a lot easier to write correctly. C++ classes allow for easy resource management. std::unique_ptr and std::shared_ptr will do 95% of the resource management you'll ever need, and std::weak_ptr will do much of the rest when judiciously applied. C++ templates, while hideous when written, allow things that C can't do at all well. std::sort is potentially much faster than qsort(), and easier to use. The C++ container/iterator/algorithm model from the STL is extremely powerful.
C++ has a whole lot more ways to handle program complexity than C does, and when you get into large code bases that makes a real difference.