Additionally, the "heavy" mode was in fact rewritten (and moved from C++ to JS). The old one wasn't computing any information that was useful.
The "heavy" view in the profiler reported incorrect information when recursive function calls were involved. The default view (top-down) of the profiler worked fine, and the heavy view worked correctly when recursion was not involved. The core of the profiler, where the real work is done and the data is actually collected, also functioned correctly.
All in all, I think boucher's reasoning behind this seemingly crucial title was to get people excited about the "enhanced" WebKit profiler, not to somehow imply the WebKit team has never done any work on this problem before or something. I'm not sure that many people would have cared that much if he'd written "minor/some bug fixes to safari profiler", especially if they had already encountered some of these bugs in the past and had been turned off by them initially, not to mention that the changes were indeed pretty significant.
Trust us, we know the frustration. We love WebKit at 280 North and are constantly saddened to hear that a lot of people don't even know about any of WebKit's truly great debugging facilities.
We're all better off if we focus on doing great things and set the sensationalism aside. Thanks again for the contributions to WebKit, and I hope there are more going forwards!