Based on the crash reports (none of the crashes have any obvious connection, and they all occur in the same memory region despite having different signatures) and the fact this happens in multiple browsers, this appears to be a hardware issue with your computer. Try resetting the computer using the steps at https://discussions.apple.com/docs/DOC-6552. If the issue continues, you should try an apple store (if you have one nearby) or a repair shop.

Also, I would suggest running apple hardware test (instructions at https://support.apple.com/en-us/HT201257). If your computer is mid-2013 or newer, you will need to use https://support.apple.com/en-us/HT202731 instead.

I'll run some memory tests and see what comes up, thanks for reading the reports!

If the memory comes back healthy, what should I try next?

Apple hardware test sometimes misses an error, so you could try running a different memory test. Most of the others are more comprehensive, but also harder to run. If you can, I would strongly suggest taking the computer to an apple store or a repair shop. It's possible there's something different going on that is causing the memory issue, and the apple store will be able to figure this out much easier than this forum can.

If your computer is older or you have a lot of things open, you could be running out of memory and using the hard drive instead, which might have a problem. You could try checking the hard drive using http://osxdaily.com/2012/05/24/check-hard-drive-health-mac-disk-utility/

Also, you might want to try the apple support forum, as there are a lot more people there who know a lot about this.