After loading a page which makes use of the newfangled CSS reflections, gradients and transitions, WebKit will consistently crash in: 0 com.apple.JavaScriptCore 0x0031790c WTF::fastFree(void*) + 508 The rest of the stack trace differs from crash to crash, but it's always in WTF::fastFree and always after loading a reflection laden page.
Can you please provide a crash log, and a page on which you can reproduce the crash? Simply mentioning that the crash is inside "free" does not provide enough useful information to debug the problem.
Kay, as Mark said, we need full crash log and exact steps to reproduce the problem. Without these informations we unable to proceed with this bug report. I have to close this bug. Feel free to reopen it if you provide requested details.