Created attachment 344380 [details]
Crash log

The following assertion failure is seen with legacy-animation-engine/animations/animation-css-rule-types.html:

ASSERTION FAILED: An attempt to dispatch an event on a stopped target by EventTargetInterface=41 (nodeName=DIV target=0x147203058 owner=0x147203058)
!target.scriptExecutionContext()->activeDOMObjectsAreStopped()
./dom/GenericEventQueue.cpp(72) : void WebCore::GenericEventQueue::dispatchOneEvent()
1   0x109b12549 WTFCrash
2   0x1123b7611 WebCore::GenericEventQueue::dispatchOneEvent()
3   0x1123bf620 WTF::Function<void ()>::CallableWrapper<std::__1::__bind<void (WebCore::GenericEventQueue::*)(), WebCore::GenericEventQueue*> >::call()
4   0x11051f2bb WTF::Function<void ()>::operator()() const
5   0x110c85029 WebCore::GenericTaskQueue<WebCore::Timer>::enqueueTask(WTF::Function<void ()>&&)::'lambda'()::operator()() const
6   0x110c84e39 WTF::Function<void ()>::CallableWrapper<WebCore::GenericTaskQueue<WebCore::Timer>::enqueueTask(WTF::Function<void ()>&&)::'lambda'()>::call()
7   0x11051f2bb WTF::Function<void ()>::operator()() const
8   0x112e4c907 WebCore::TaskDispatcher<WebCore::Timer>::dispatchOneTask()
9   0x112e4c6bf WebCore::TaskDispatcher<WebCore::Timer>::sharedTimerFired()
10  0x112e50c41 WebCore::TaskDispatcher<WebCore::Timer>::sharedTimer()::$_1::operator()() const
11  0x112e50c09 WTF::Function<void ()>::CallableWrapper<WebCore::TaskDispatcher<WebCore::Timer>::sharedTimer()::$_1>::call()
12  0x11051f2bb WTF::Function<void ()>::operator()() const
13  0x110572029 WebCore::Timer::fired()
14  0x112e857d0 WebCore::ThreadTimers::sharedTimerFiredInternal()
15  0x112e9b201 WebCore::ThreadTimers::setSharedTimer(WebCore::SharedTimer*)::$_0::operator()() const
16  0x112e9b1b9 WTF::Function<void ()>::CallableWrapper<WebCore::ThreadTimers::setSharedTimer(WebCore::SharedTimer*)::$_0>::call()
17  0x11051f2bb WTF::Function<void ()>::operator()() const
18  0x112e5d4c5 WebCore::MainThreadSharedTimer::fired()
19  0x112f03b69 WebCore::timerFired(__CFRunLoopTimer*, void*)
20  0x7fff7653de04 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
21  0x7fff7653da93 __CFRunLoopDoTimer
22  0x7fff7653d5ea __CFRunLoopDoTimers
23  0x7fff76534fc1 __CFRunLoopRun
24  0x7fff76534544 CFRunLoopRunSpecific
25  0x7fff75a93ebc RunCurrentEventLoopInMode
26  0x7fff75a93cf1 ReceiveNextEventCommon
27  0x7fff75a93b26 _BlockUntilNextEventMatchingListInModeWithFilter
28  0x7fff7402aa54 _DPSNextEvent
29  0x7fff747a67ee -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:]
30  0x7fff7401f3db -[NSApplication run]
31  0x7fff73fe9e0e NSApplicationMain
LEAK: 2 WebPageProxy

The crashlog blames a different test: legacy-animation-engine/animations/animation-controller-drt-api.html

https://build.webkit.org/results/Apple%20Sierra%20Debug%20WK2%20(Tests)/r233533%20(7136)/results.html