Reproducible in r39370 Nightly. STEPS TO REPRODUCE 1. Login to Gmail at http://gmail.com/ 2. Immediately upon mailbox list appearing start scrolling the page up and down with scrollwheel. RESULT Crash. Crash report to be attached.
Created attachment 26130 [details] Crash report
I can confirm this.
I couldn't repro this bug on X, but I think this dupes a Windows bug fixed by: https://bugs.webkit.org/show_bug.cgi?id=22974 Since I can't repro I'll assume this is fixed in the same change, please reopen if you continue to experience the problem after r39450. Cheers, G.