I don't think reinstalling 10.11.4 will fix it, but let us know. Sure would be nice, if, say, someone like APPLE would acknowledge this issue and try to fix it. Leaving users to randomly experiment on their own is something I associate with Windows, not the Mac.
Here's what I think I know about this, just to put it all in one place:
1. It doesn't matter if you've installed 10.11.4 via the updater or the combo updater. People who've done each of those report the same type of crash.
2. The crashes I've seen have been in Safari, and once in Photos.
3. It isn't clear if the Safari Technology Preview (1 or 2) solves this.
4. The crashes are mostly (perhaps exclusively) reported on Macs with Intel Iris Graphics. BTW, if anyone has this crash who does NOT use Intel Iris Graphics, report that, because that would be very important information.
5. Without running afoul of the "you can't talk about beta software", let me say that there is no release of OS X subsequent to 10.11.3 that fixes this problem.
6. For me at least, all this started when I installed 10.11.4 via the combo updater.
7. If you get really desperate, see my post earlier in this thread about how to roll back to 10.11.3 and keep all your user files in their current stat.
To consolidate information, if anyone has anything to add to the above list, I'd suggest replying to this post, keeping the list and appending more bits of information. Hopefully Apple will eventually pay some attention to this.