core dumped

[Geordie]

uname -a
FreeBSD geordieslaptop.home.network 11.0-STABLE FreeBSD 11.0-STABLE #2
r317644: Mon May  1 11:43:03 EDT 2017 

firefox-53.0.2,1

Actually I was running 53.0_2,1 yesterday and when rebooted the
machine firefox was kind enough to give me a core dump  and this message

May 12 12:53:14 geordieslaptop kernel: pid 4202 (firefox), uid 1001:
exited on signal 11 (core dumped)
I upgraded to firefox-53.0.2,1 and gave me the same error

Let me know if you want the core dump It is 11.1MiB

Geordie