+++ This bug was initially created as a clone of Bug #1594632 +++
./mach crashtest --verify layout/style/crashtests/1593766.html

[Child 162493, Main Thread] ###!!! ASSERTION: Failed Dispatch after xpcom-shutdown-threads: 'false', file /home/karl/moz/dev/xpcom/threads/ThreadEventTarget.cpp, line 117
#01: mozilla::ThreadEventTarget::Dispatch(already_AddRefed<nsIRunnable>, unsigned int) (/home/karl/moz/dev/xpcom/threads/ThreadEventTarget.cpp:117)
#02: nsThread::Dispatch(already_AddRefed<nsIRunnable>, unsigned int) (/home/karl/moz/dev/xpcom/threads/nsThread.cpp:719)
#03: mozilla::dom::WorkletThread::DispatchRunnable(already_AddRefed<nsIRunnable>) (/home/karl/moz/dev/dom/worklet/WorkletThread.cpp:281)
#04: mozilla::dom::WorkletThread::Create(mozilla::WorkletImpl*) (/home/karl/moz/dev/dom/worklet/WorkletThread.cpp:271)
#05: mozilla::WorkletImpl::SendControlMessage(already_AddRefed<nsIRunnable>) (/home/karl/moz/dev/dom/worklet/WorkletImpl.cpp:116)
#06: mozilla::WorkletImpl::NotifyWorkletFinished() (/home/karl/moz/dev/dom/worklet/WorkletImpl.cpp:92)
#07: ~Worklet (/home/karl/moz/dev/dom/worklet/Worklet.cpp:446)
#08: mozilla::dom::Worklet::DeleteCycleCollectable() (/home/karl/moz/dev/dom/worklet/Worklet.cpp:427)
#09: mozilla::dom::Worklet::cycleCollection::DeleteCycleCollectable(void*) (/home/karl/moz/dev/dom/worklet/Worklet.h:32)
#10: SnowWhiteKiller::MaybeKillObject(SnowWhiteKiller::SnowWhiteObject&) (pthread_atfork.c:?)
#11: ~SnowWhiteKiller (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:2415)
#12: nsCycleCollector::FreeSnowWhite(bool) (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:2610)
#13: nsCycleCollector::BeginCollection(ccType, nsICycleCollectorListener*) (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:3586)
#14: nsCycleCollector::Collect(ccType, js::SliceBudget&, nsICycleCollectorListener*, bool) (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:3415)
#15: nsCycleCollector::ShutdownCollect() (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:3358)
#16: nsCycleCollector::Shutdown(bool) (pthread_atfork.c:?)
#17: nsCycleCollector_shutdown(bool) (/home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp:3961)
#18: mozilla::ShutdownXPCOM(nsIServiceManager*) (/home/karl/moz/dev/xpcom/build/XPCOMInit.cpp:716)
#19: NS_ShutdownXPCOM (/home/karl/moz/dev/xpcom/build/XPCOMInit.cpp:569)
#20: XRE_TermEmbedding() (/home/karl/moz/dev/toolkit/xre/nsEmbedFunctions.cpp:227)
#21: mozilla::ipc::ScopedXREEmbed::Stop() (/home/karl/moz/dev/ipc/glue/ScopedXREEmbed.cpp:90)
#22: mozilla::dom::ContentProcess::CleanUp() (/home/karl/moz/dev/dom/ipc/ContentProcess.cpp:211)
#23: XRE_InitChildProcess(int, char**, XREChildData const*) (/home/karl/moz/dev/toolkit/xre/nsEmbedFunctions.cpp:783)
#24: mozilla::BootstrapImpl::XRE_InitChildProcess(int, char**, XREChildData const*) (/home/karl/moz/dev/toolkit/xre/Bootstrap.cpp:67)
#25: content_process_main(mozilla::Bootstrap*, int, char**) (/home/karl/moz/dev/browser/app/../../ipc/contentproc/plugin-container.cpp:56)
#26: main (/home/karl/moz/dev/browser/app/nsBrowserApp.cpp:303)
#27: __libc_start_main (/var/tmp/portage/sys-libs/glibc-2.29-r7/work/glibc-2.29/csu/../csu/libc-start.c:342)
#28: _start (/var/karl/moz/obj/dist/bin/firefox)
#29: ??? (???:???)
[Child 162493, Main Thread] WARNING: 'NS_FAILED(thread->DispatchRunnable(runnable.forget()))', file /home/karl/moz/dev/dom/worklet/WorkletThread.cpp, line 271
[Child 162493, Main Thread] WARNING: Extra shutdown CC: 'i < NORMAL_SHUTDOWN_COLLECTIONS', file /home/karl/moz/dev/xpcom/base/nsCycleCollector.cpp, line 3362
Assertion failure: isEmpty() (failing this assertion means this LinkedList's creator is buggy: it should have removed all this list's elements before the list's destruction), at /var/karl/moz/obj/dist/include/mozilla/LinkedList.h:434
#01: ~LinkedList (/var/karl/moz/obj/dist/include/mozilla/LinkedList.h:431)
#02: __run_exit_handlers (/var/tmp/portage/sys-libs/glibc-2.29-r7/work/glibc-2.29/stdlib/exit.c:109)
#03: __GI_exit (:?)
#04: __libc_start_main (/var/tmp/portage/sys-libs/glibc-2.29-r7/work/glibc-2.29/csu/../csu/libc-start.c:261)
#05: _start (/var/karl/moz/obj/dist/bin/firefox)
#06: ??? (???:???)

to catch if any threads are created between xpcom-shutdown and
xpcom-shutdown-threads.

Closing because no crashes reported for 12 weeks.