Curious why you say that, as Chrome is definitely a different project than WebKit (obviously they use it, but they defer rendering issues to the main WebKit tracker), and I’m not sure how much Google throws at WebKit. Also, do you me currently, or cumulatively?

If you measure by number of commits (whatever that's worth), data is at http://neugierig.org/software/chromium/notes/2010/02/webkit-...

So the answers for "currently" and "cumulatively" differ at least by this metric. And the metric itself is questionable, as the blog post says.