Reduced with m-c 20200520-855249e545c3

Assertion failure: currentBC && mOwnerBrowsingContext, at /builds/worker/checkouts/gecko/dom/html/HTMLMediaElement.cpp:518

0|0|libxul.so|mozilla::dom::HTMLMediaElement::MediaControlEventListener::UpdateOwnerBrowsingContextIfNeeded()|hg:hg.mozilla.org/mozilla-central:dom/html/HTMLMediaElement.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|518|0x29
0|1|libxul.so|mozilla::dom::HTMLMediaElement::BindToTree(mozilla::dom::BindContext&, nsINode&)|hg:hg.mozilla.org/mozilla-central:dom/html/HTMLMediaElement.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|4691|0x10
0|2|libxul.so|nsINode::InsertChildBefore(nsIContent*, nsIContent*, bool)|hg:hg.mozilla.org/mozilla-central:dom/base/nsINode.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1520|0x12
0|3|libxul.so|nsINode::ReplaceOrInsertBefore(bool, nsINode*, nsINode*, mozilla::ErrorResult&)|hg:hg.mozilla.org/mozilla-central:dom/base/nsINode.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|2663|0x1b
0|4|libxul.so|nsINode::Append(mozilla::dom::Sequence<mozilla::dom::OwningNodeOrString> const&, mozilla::ErrorResult&)|hg:hg.mozilla.org/mozilla-central:dom/base/nsINode.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|2025|0x17
0|5|libxul.so|mozilla::dom::Element_Binding::append(JSContext*, JS::Handle<JSObject*>, void*, JSJitMethodCallArgs const&)|s3:gecko-generated-sources:d94184b12b100ccf230989a3ba17cf107b91baff26e9351904334de20cfafa2cdb30d77ecce08ea0455212ea3522c1aabebf0f19bcf0f37b8fbaedbc7e683c63/dom/bindings/ElementBinding.cpp:|9941|0xb
0|6|libxul.so|bool mozilla::dom::binding_detail::GenericMethod<mozilla::dom::binding_detail::NormalThisPolicy, mozilla::dom::binding_detail::ThrowExceptions>(JSContext*, unsigned int, JS::Value*)|hg:hg.mozilla.org/mozilla-central:dom/bindings/BindingUtils.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|3203|0x21
0|7|libxul.so|CallJSNative(JSContext*, bool (*)(JSContext*, unsigned int, JS::Value*), js::CallReason, JS::CallArgs const&)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|493|0x12
0|8|libxul.so|js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|585|0x12
0|9|libxul.so|Interpret(JSContext*, js::RunState&)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|652|0x7
0|10|libxul.so|js::RunScript(JSContext*, js::RunState&)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|465|0xb
0|11|libxul.so|js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|620|0xd
0|12|libxul.so|<name omitted>|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|665|0xb
0|13|libxul.so|JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>)|hg:hg.mozilla.org/mozilla-central:js/src/jsapi.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|2840|0x23
0|14|libxul.so|mozilla::dom::EventHandlerNonNull::Call(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, mozilla::dom::Event&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&)|s3:gecko-generated-sources:a39a0c7064327d8bf5f33af316b4cc9c9d3236184b2183673b9f8103182682809cdd62ab814947d309a2f0405582be39e80ec6d762aad6de8c66e51e15d2f95d/dom/bindings/EventHandlerBinding.cpp:|276|0xb
0|15|libxul.so|void mozilla::dom::EventHandlerNonNull::Call<nsCOMPtr<mozilla::dom::EventTarget> >(nsCOMPtr<mozilla::dom::EventTarget> const&, mozilla::dom::Event&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&, char const*, mozilla::dom::CallbackObject::ExceptionHandling, JS::Realm*)|s3:gecko-generated-sources:5abc72777d30ad0ea7b8b3e1392cd7961bd73b8cd08e5ab209f3b42251def563ee9c9a7cea98a24d0fa9d867edfc0c0297c165b0d167458ac5a2af4b7a0caebe/dist/include/mozilla/dom/EventHandlerBinding.h:|367|0x28
0|16|libxul.so|mozilla::JSEventHandler::HandleEvent(mozilla::dom::Event*)|hg:hg.mozilla.org/mozilla-central:dom/events/JSEventHandler.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|201|0x18
0|17|libxul.so|mozilla::EventListenerManager::HandleEventSubType(mozilla::EventListenerManager::Listener*, mozilla::dom::Event*, mozilla::dom::EventTarget*)|hg:hg.mozilla.org/mozilla-central:dom/events/EventListenerManager.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1088|0xc
0|18|libxul.so|mozilla::EventListenerManager::HandleEventInternal(nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event**, mozilla::dom::EventTarget*, nsEventStatus*, bool)|hg:hg.mozilla.org/mozilla-central:dom/events/EventListenerManager.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1280|0x15
0|19|libxul.so|mozilla::EventTargetChainItem::HandleEvent(mozilla::EventChainPostVisitor&, mozilla::ELMCreationDetector&)|hg:hg.mozilla.org/mozilla-central:dom/events/EventDispatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|356|0xb
0|20|libxul.so|mozilla::EventTargetChainItem::HandleEventTargetChain(nsTArray<mozilla::EventTargetChainItem>&, mozilla::EventChainPostVisitor&, mozilla::EventDispatchingCallback*, mozilla::ELMCreationDetector&)|hg:hg.mozilla.org/mozilla-central:dom/events/EventDispatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|558|0x19
0|21|libxul.so|mozilla::EventDispatcher::Dispatch(nsISupports*, nsPresContext*, mozilla::WidgetEvent*, mozilla::dom::Event*, nsEventStatus*, mozilla::EventDispatchingCallback*, nsTArray<mozilla::dom::EventTarget*>*)|hg:hg.mozilla.org/mozilla-central:dom/events/EventDispatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1055|0x5
0|22|libxul.so|mozilla::EventDispatcher::DispatchDOMEvent(nsISupports*, mozilla::WidgetEvent*, mozilla::dom::Event*, nsPresContext*, nsEventStatus*)|hg:hg.mozilla.org/mozilla-central:dom/events/EventDispatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|0|0x8
0|23|libxul.so|nsINode::DispatchEvent(mozilla::dom::Event&, mozilla::dom::CallerType, mozilla::ErrorResult&)|hg:hg.mozilla.org/mozilla-central:dom/base/nsINode.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1302|0x10
0|24|libxul.so|mozilla::dom::EventTarget::DispatchEvent(mozilla::dom::Event&)|hg:hg.mozilla.org/mozilla-central:dom/events/EventTarget.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|178|0x33
0|25|libxul.so|mozilla::AsyncEventDispatcher::Run()|hg:hg.mozilla.org/mozilla-central:dom/events/AsyncEventDispatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|69|0x22
0|26|libxul.so|mozilla::SchedulerGroup::Runnable::Run()|hg:hg.mozilla.org/mozilla-central:xpcom/threads/SchedulerGroup.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|146|0x11
0|27|libxul.so|nsThread::ProcessNextEvent(bool, bool*)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsThread.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1211|0x11
0|28|libxul.so|NS_ProcessNextEvent(nsIThread*, bool)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsThreadUtils.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|501|0xc
0|29|libxul.so|bool mozilla::SpinEventLoopUntil<(mozilla::ProcessFailureBehavior)1, mozilla::dom::ContentChild::ProvideWindowCommon(mozilla::dom::BrowserChild*, nsIOpenWindowInfo*, unsigned int, bool, bool, nsIURI*, nsTSubstring<char16_t> const&, nsTSubstring<char> const&, bool, bool, nsDocShellLoadState*, bool*, mozilla::dom::BrowsingContext**)::$_9>(mozilla::dom::ContentChild::ProvideWindowCommon(mozilla::dom::BrowserChild*, nsIOpenWindowInfo*, unsigned int, bool, bool, nsIURI*, nsTSubstring<char16_t> const&, nsTSubstring<char> const&, bool, bool, nsDocShellLoadState*, bool*, mozilla::dom::BrowsingContext**)::$_9&&, nsIThread*)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsThreadUtils.h:855249e545c361516a65bcba8f5bc6b423e2d131|359|0xd
0|30|libxul.so|mozilla::dom::ContentChild::ProvideWindowCommon(mozilla::dom::BrowserChild*, nsIOpenWindowInfo*, unsigned int, bool, bool, nsIURI*, nsTSubstring<char16_t> const&, nsTSubstring<char> const&, bool, bool, nsDocShellLoadState*, bool*, mozilla::dom::BrowsingContext**)|hg:hg.mozilla.org/mozilla-central:dom/ipc/ContentChild.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1179|0xf
0|31|libxul.so|mozilla::dom::BrowserChild::ProvideWindow(nsIOpenWindowInfo*, unsigned int, bool, bool, nsIURI*, nsTSubstring<char16_t> const&, nsTSubstring<char> const&, bool, bool, nsDocShellLoadState*, bool*, mozilla::dom::BrowsingContext**)|hg:hg.mozilla.org/mozilla-central:dom/ipc/BrowserChild.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|887|0x34
0|32|libxul.so|nsWindowWatcher::OpenWindowInternal(mozIDOMWindowProxy*, char const*, char const*, char const*, bool, bool, bool, nsIArray*, bool, bool, bool, nsDocShellLoadState*, mozilla::dom::BrowsingContext**)|hg:hg.mozilla.org/mozilla-central:toolkit/components/windowwatcher/nsWindowWatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|830|0x48
0|33|libxul.so|nsWindowWatcher::OpenWindow2(mozIDOMWindowProxy*, char const*, char const*, char const*, bool, bool, bool, nsISupports*, bool, bool, bool, nsDocShellLoadState*, mozilla::dom::BrowsingContext**)|hg:hg.mozilla.org/mozilla-central:toolkit/components/windowwatcher/nsWindowWatcher.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|375|0x41
0|34|libxul.so|nsGlobalWindowOuter::OpenInternal(nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, bool, bool, bool, bool, bool, nsIArray*, nsISupports*, nsDocShellLoadState*, bool, mozilla::dom::BrowsingContext**)|hg:hg.mozilla.org/mozilla-central:dom/base/nsGlobalWindowOuter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|7072|0x64
0|35|libxul.so|nsGlobalWindowOuter::OpenOuter(nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, mozilla::ErrorResult&)|hg:hg.mozilla.org/mozilla-central:dom/base/nsGlobalWindowOuter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|5634|0x41
0|36|libxul.so|nsGlobalWindowInner::Open(nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, nsTSubstring<char16_t> const&, mozilla::ErrorResult&)|hg:hg.mozilla.org/mozilla-central:dom/base/nsGlobalWindowInner.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|3765|0x27
0|37|libxul.so|mozilla::dom::Window_Binding::open(JSContext*, JS::Handle<JSObject*>, void*, JSJitMethodCallArgs const&)|s3:gecko-generated-sources:3a994aaac84a9765a57acb433929781c03a9f1a9c8c76965c8061742ca7be71976df9075d40e78d295a16f900a0f4f0991546be7009fc3b8ca626fbab5a72b8d/dom/bindings/WindowBinding.cpp:|2701|0x35
0|38|libxul.so|bool mozilla::dom::binding_detail::GenericMethod<mozilla::dom::binding_detail::MaybeCrossOriginObjectThisPolicy, mozilla::dom::binding_detail::ThrowExceptions>(JSContext*, unsigned int, JS::Value*)|hg:hg.mozilla.org/mozilla-central:dom/bindings/BindingUtils.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|3203|0x1e
0|39|libxul.so|CallJSNative(JSContext*, bool (*)(JSContext*, unsigned int, JS::Value*), js::CallReason, JS::CallArgs const&)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|493|0x12
0|40|libxul.so|js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|585|0x12
0|41|libxul.so|js::jit::DoCallFallback(JSContext*, js::jit::BaselineFrame*, js::jit::ICCall_Fallback*, unsigned int, JS::Value*, JS::MutableHandle<JS::Value>)|hg:hg.mozilla.org/mozilla-central:js/src/jit/BaselineIC.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|2990|0x8
0|42|||||0x382c4ce2ed3
0|43|||||0x55fb18510b28
0|44|||||0x382c4cd8b04
0|45|libxul.so|js::jit::MaybeEnterJit(JSContext*, js::RunState&)|hg:hg.mozilla.org/mozilla-central:js/src/jit/Jit.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|196|0x4a3
0|46|libxul.so|js::RunScript(JSContext*, js::RunState&)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|450|0xb
0|47|libxul.so|js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason)|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|620|0xd
0|48|libxul.so|<name omitted>|hg:hg.mozilla.org/mozilla-central:js/src/vm/Interpreter.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|665|0xb
0|49|libxul.so|JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>)|hg:hg.mozilla.org/mozilla-central:js/src/jsapi.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|2840|0x23
0|50|libxul.so|mozilla::dom::Function::Call(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, nsTArray<JS::Value> const&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&)|s3:gecko-generated-sources:e1b4e4cc33e7b0d89c05155298fabe650071ceecb2d762b5e176a870c3090b87377a846cd26b1af06573d0c39be355f717cfa4eba916206f8b22172a9046cbab/dom/bindings/FunctionBinding.cpp:|43|0x15
0|51|libxul.so|void mozilla::dom::Function::Call<nsCOMPtr<nsIGlobalObject> >(nsCOMPtr<nsIGlobalObject> const&, nsTArray<JS::Value> const&, JS::MutableHandle<JS::Value>, mozilla::ErrorResult&, char const*, mozilla::dom::CallbackObject::ExceptionHandling, JS::Realm*)|s3:gecko-generated-sources:84e03935fdea6287f0d6a93c3773f53d63702c33eff1dc7fa1beeb370d1cda84415dec66ac541edf01d400fc11986cda3c1ea3516669f568ec58173017beff94/dist/include/mozilla/dom/FunctionBinding.h:|73|0x28
0|52|libxul.so|mozilla::dom::CallbackTimeoutHandler::Call(char const*)|hg:hg.mozilla.org/mozilla-central:dom/base/TimeoutHandler.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|167|0x2b
0|53|libxul.so|nsGlobalWindowInner::RunTimeoutHandler(mozilla::dom::Timeout*, nsIScriptContext*)|hg:hg.mozilla.org/mozilla-central:dom/base/nsGlobalWindowInner.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|5947|0x18
0|54|libxul.so|mozilla::dom::TimeoutManager::RunTimeout(mozilla::TimeStamp const&, mozilla::TimeStamp const&, bool)|hg:hg.mozilla.org/mozilla-central:dom/base/TimeoutManager.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|891|0x8
0|55|libxul.so|mozilla::dom::TimeoutExecutor::MaybeExecute()|hg:hg.mozilla.org/mozilla-central:dom/base/TimeoutExecutor.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|179|0x15
0|56|libxul.so|non-virtual thunk to mozilla::dom::TimeoutExecutor::Notify(nsITimer*)|hg:hg.mozilla.org/mozilla-central:dom/base/TimeoutExecutor.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|0|0x13
0|57|libxul.so|nsTimerImpl::Fire(int)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsTimerImpl.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|564|0xe
0|58|libxul.so|nsTimerEvent::Run()|hg:hg.mozilla.org/mozilla-central:xpcom/threads/TimerThread.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|250|0x14
0|59|libxul.so|mozilla::ThrottledEventQueue::Inner::ExecuteRunnable()|hg:hg.mozilla.org/mozilla-central:xpcom/threads/ThrottledEventQueue.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|254|0x11
0|60|libxul.so|mozilla::ThrottledEventQueue::Inner::Executor::Run()|hg:hg.mozilla.org/mozilla-central:xpcom/threads/ThrottledEventQueue.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|81|0x11
0|61|libxul.so|nsThread::ProcessNextEvent(bool, bool*)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsThread.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|1211|0x11
0|62|libxul.so|NS_ProcessNextEvent(nsIThread*, bool)|hg:hg.mozilla.org/mozilla-central:xpcom/threads/nsThreadUtils.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|501|0xc
0|63|libxul.so|mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*)|hg:hg.mozilla.org/mozilla-central:ipc/glue/MessagePump.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|109|0x14
0|64|libxul.so|MessageLoop::RunInternal()|hg:hg.mozilla.org/mozilla-central:ipc/chromium/src/base/message_loop.cc:855249e545c361516a65bcba8f5bc6b423e2d131|315|0x17
0|65|libxul.so|MessageLoop::Run()|hg:hg.mozilla.org/mozilla-central:ipc/chromium/src/base/message_loop.cc:855249e545c361516a65bcba8f5bc6b423e2d131|290|0x8
0|66|libxul.so|nsBaseAppShell::Run()|hg:hg.mozilla.org/mozilla-central:widget/nsBaseAppShell.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|137|0xd
0|67|libxul.so|XRE_RunAppShell()|hg:hg.mozilla.org/mozilla-central:toolkit/xre/nsEmbedFunctions.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|909|0xe
0|68|libxul.so|mozilla::ipc::MessagePumpForChildProcess::Run(base::MessagePump::Delegate*)|hg:hg.mozilla.org/mozilla-central:ipc/glue/MessagePump.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|237|0x5
0|69|libxul.so|MessageLoop::RunInternal()|hg:hg.mozilla.org/mozilla-central:ipc/chromium/src/base/message_loop.cc:855249e545c361516a65bcba8f5bc6b423e2d131|315|0x17
0|70|libxul.so|MessageLoop::Run()|hg:hg.mozilla.org/mozilla-central:ipc/chromium/src/base/message_loop.cc:855249e545c361516a65bcba8f5bc6b423e2d131|290|0x8
0|71|libxul.so|XRE_InitChildProcess(int, char**, XREChildData const*)|hg:hg.mozilla.org/mozilla-central:toolkit/xre/nsEmbedFunctions.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|740|0x5
0|72|firefox-bin|content_process_main(mozilla::Bootstrap*, int, char**)|hg:hg.mozilla.org/mozilla-central:ipc/contentproc/plugin-container.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|56|0x11
0|73|firefox-bin|main|hg:hg.mozilla.org/mozilla-central:browser/app/nsBrowserApp.cpp:855249e545c361516a65bcba8f5bc6b423e2d131|303|0x20

A Pernosco session is available here: https://pernos.co/debug/iWgyBwunsVdOCyFDYCdT9g/index.html

Now I'm working on bug 1640998 and its solution might fix this issue as well.

Adding [fission-] whiteboard tab because this is not a Fission bug, even though it is a BrowsingContext assertion failure.

That assertion has been removed in bug 1640998, so close this bug.