https://bugzilla.mozilla.org/show_bug.cgi?id=1580921
1580921 - Improve thread-safety checks on mozilla::WeakPtr
RESOLVED (honzab.moz) in Core - MFBT. Last updated 2019-09-16.
safety checksimprovethreadmozilla
https://bugzilla.mozilla.org/show_bug.cgi?id=1257296
1257296 - WeakPtr should not silently behave badly when you null check it
RESOLVED (nobody) in Core - MFBT. Last updated 2016-03-23.
should not