New bug to report, easy to reproduce in r77220. Open a new window and start typing into the built-in google search bar. Just a few letters are enough and you can stop for a second, or two and boom the browser crashes. Might have something to do with the exchange of suggestions google does. I'm attaching a crash report. I have extensions disabled and have absolutely no Safari/Webkit extras. Returning to r77034 resolves the issue.
Created attachment 80776 [details] Crash Report
*** Bug 53507 has been marked as a duplicate of this bug. ***
<rdar://problem/8943651>
*** Bug 53486 has been marked as a duplicate of this bug. ***
*** This bug has been marked as a duplicate of bug 53519 ***