Found while fuzzing m-c 20240610-c6d003a3edf3 (--enable-debug --enable-fuzzing)

To reproduce via Grizzly Replay:

$ pip install fuzzfetch grizzly-framework --upgrade
$ python -m fuzzfetch -d --fuzzing -n firefox
$ python -m grizzly.replay.bugzilla ./firefox/firefox <bugid>

Assertion failure: SVGUtils::AnyOuterSVGIsCallingReflowSVG(this) (This call is probably a wasteful mistake), at /builds/worker/checkouts/gecko/layout/svg/SVGContainerFrame.cpp:305

#0 0x7ffa6a3c3d91 in mozilla::SVGDisplayContainerFrame::ReflowSVG() /builds/worker/checkouts/gecko/layout/svg/SVGContainerFrame.cpp:304:3
#1 0x7ffa6a3eb8f8 in mozilla::SVGSwitchFrame::ReflowSVG() /builds/worker/checkouts/gecko/layout/svg/SVGSwitchFrame.cpp:197:15
#2 0x7ffa6a3c3a98 in mozilla::SVGDisplayContainerFrame::ReflowSVG() /builds/worker/checkouts/gecko/layout/svg/SVGContainerFrame.cpp:337:17
#3 0x7ffa6a3e6a4a in mozilla::SVGOuterSVGFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/svg/SVGOuterSVGFrame.cpp:404:14
#4 0x7ffa6a1ddbee in nsAbsoluteContainingBlock::ReflowAbsoluteFrame(nsIFrame*, nsPresContext*, mozilla::ReflowInput const&, nsRect const&, nsAbsoluteContainingBlock::AbsPosReflowFlags, nsIFrame*, nsReflowStatus&, mozilla::OverflowAreas*) /builds/worker/checkouts/gecko/layout/generic/nsAbsoluteContainingBlock.cpp:811:14
#5 0x7ffa6a1dc11b in nsAbsoluteContainingBlock::Reflow(nsContainerFrame*, nsPresContext*, mozilla::ReflowInput const&, nsReflowStatus&, nsRect const&, nsAbsoluteContainingBlock::AbsPosReflowFlags, mozilla::OverflowAreas*) /builds/worker/checkouts/gecko/layout/generic/nsAbsoluteContainingBlock.cpp:219:7
#6 0x7ffa6a2a00f1 in nsIFrame::ReflowAbsoluteFrames(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&, bool) /builds/worker/checkouts/gecko/layout/generic/nsIFrame.cpp:6960:24
#7 0x7ffa6a2edfe7 in nsPageContentFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/nsPageContentFrame.cpp:141:3
#8 0x7ffa6a21f111 in nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, int, int, nsIFrame::ReflowChildFlags, nsReflowStatus&, nsOverflowContinuationTracker*) /builds/worker/checkouts/gecko/layout/generic/nsContainerFrame.cpp:930:14
#9 0x7ffa6a2f0439 in nsPageFrame::ReflowPageContent(nsPresContext*, mozilla::ReflowInput const&) /builds/worker/checkouts/gecko/layout/generic/nsPageFrame.cpp:199:3
#10 0x7ffa6a2f0fde in nsPageFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/nsPageFrame.cpp:221:13
#11 0x7ffa6a215e04 in nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, mozilla::WritingMode const&, mozilla::LogicalPoint const&, nsSize const&, nsIFrame::ReflowChildFlags, nsReflowStatus&, nsOverflowContinuationTracker*) /builds/worker/checkouts/gecko/layout/generic/nsContainerFrame.cpp:889:14
#12 0x7ffa6a19327a in mozilla::PrintedSheetFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/PrintedSheetFrame.cpp:170:5
#13 0x7ffa6a21f111 in nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, int, int, nsIFrame::ReflowChildFlags, nsReflowStatus&, nsOverflowContinuationTracker*) /builds/worker/checkouts/gecko/layout/generic/nsContainerFrame.cpp:930:14
#14 0x7ffa6a2f57c4 in nsPageSequenceFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/nsPageSequenceFrame.cpp:368:5
#15 0x7ffa6a215e04 in nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, mozilla::WritingMode const&, mozilla::LogicalPoint const&, nsSize const&, nsIFrame::ReflowChildFlags, nsReflowStatus&, nsOverflowContinuationTracker*) /builds/worker/checkouts/gecko/layout/generic/nsContainerFrame.cpp:889:14
#16 0x7ffa6a208fc1 in nsCanvasFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/nsCanvasFrame.cpp:717:7
#17 0x7ffa6a21f111 in nsContainerFrame::ReflowChild(nsIFrame*, nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, int, int, nsIFrame::ReflowChildFlags, nsReflowStatus&, nsOverflowContinuationTracker*) /builds/worker/checkouts/gecko/layout/generic/nsContainerFrame.cpp:930:14
#18 0x7ffa6a1db330 in mozilla::ViewportFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) /builds/worker/checkouts/gecko/layout/generic/ViewportFrame.cpp:356:7
#19 0x7ffa6a0a5b20 in mozilla::PresShell::DoReflow(nsIFrame*, bool, mozilla::OverflowChangedTracker*) /builds/worker/checkouts/gecko/layout/base/PresShell.cpp:9833:11
#20 0x7ffa6a0cef6f in mozilla::PresShell::ProcessReflowCommands(bool) /builds/worker/checkouts/gecko/layout/base/PresShell.cpp:10006:22
#21 0x7ffa6a0afac7 in DoFlushLayout /builds/worker/checkouts/gecko/layout/base/PresShell.cpp:10053:10
#22 0x7ffa6a0afac7 in mozilla::PresShell::DoFlushPendingNotifications(mozilla::ChangesToFlush) /builds/worker/checkouts/gecko/layout/base/PresShell.cpp:4366:9
#23 0x7ffa6a512ec2 in FlushPendingNotifications /builds/worker/workspace/obj-build/dist/include/mozilla/PresShell.h:1446:5
#24 0x7ffa6a512ec2 in nsPrintJob::ReflowPrintObject(mozilla::UniquePtr<nsPrintObject, mozilla::DefaultDelete<nsPrintObject>> const&) /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:1423:14
#25 0x7ffa6a512277 in nsPrintJob::ReflowDocList(mozilla::UniquePtr<nsPrintObject, mozilla::DefaultDelete<nsPrintObject>> const&) /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:959:3
#26 0x7ffa6a50f27f in nsPrintJob::InitPrintDocConstruction(bool) /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:1000:5
#27 0x7ffa6a50e1fb in nsPrintJob::DoCommonPrint(bool, nsIPrintSettings*, nsIWebProgressListener*, mozilla::dom::Document&) /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:446:3
#28 0x7ffa6a50f455 in CommonPrint /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:335:17
#29 0x7ffa6a50f455 in nsPrintJob::Print(mozilla::dom::Document&, nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*) /builds/worker/checkouts/gecko/layout/printing/nsPrintJob.cpp:456:10
#30 0x7ffa6a134500 in nsDocumentViewer::Print(nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*) /builds/worker/checkouts/gecko/layout/base/nsDocumentViewer.cpp:2894:27
#31 0x7ffa66288d48 in nsGlobalWindowOuter::Print(nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*, nsIDocShell*, nsGlobalWindowOuter::IsPreview, nsGlobalWindowOuter::IsForWindowDotPrint, std::function<void (mozilla::dom::PrintPreviewResultInfo const&)>&&, RefPtr<mozilla::dom::BrowsingContext>*, mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:5230:24
#32 0x7ffa69466a7d in mozilla::dom::BrowserChild::CommonPrint(mozilla::dom::MaybeDiscarded<mozilla::dom::BrowsingContext> const&, mozilla::embedding::PrintData const&, RefPtr<mozilla::dom::BrowsingContext>*) /builds/worker/checkouts/gecko/dom/ipc/BrowserChild.cpp:2424:18
#33 0x7ffa69466dfa in mozilla::dom::BrowserChild::RecvPrint(mozilla::dom::MaybeDiscarded<mozilla::dom::BrowsingContext> const&, mozilla::embedding::PrintData const&, bool, std::function<void (mozilla::dom::MaybeDiscarded<mozilla::dom::BrowsingContext> const&)>&&) /builds/worker/checkouts/gecko/dom/ipc/BrowserChild.cpp:2443:17
#34 0x7ffa6959af26 in mozilla::dom::PBrowserChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PBrowserChild.cpp:7517:80
#35 0x7ffa6961c8e0 in mozilla::dom::PContentChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PContentChild.cpp:8155:32
#36 0x7ffa64f2b19f in mozilla::ipc::MessageChannel::DispatchAsyncMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message const&) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1820:25
#37 0x7ffa64f27ef2 in mozilla::ipc::MessageChannel::DispatchMessage(mozilla::ipc::ActorLifecycleProxy*, mozilla::UniquePtr<IPC::Message, mozilla::DefaultDelete<IPC::Message>>) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1739:9
#38 0x7ffa64f28b72 in mozilla::ipc::MessageChannel::RunMessage(mozilla::ipc::ActorLifecycleProxy*, mozilla::ipc::MessageChannel::MessageTask&) /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1530:3
#39 0x7ffa64f29cbf in mozilla::ipc::MessageChannel::MessageTask::Run() /builds/worker/checkouts/gecko/ipc/glue/MessageChannel.cpp:1630:14
#40 0x7ffa6426bd87 in mozilla::RunnableTask::Run() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:580:16
#41 0x7ffa64261786 in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:907:26
#42 0x7ffa6425ff47 in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:730:15
#43 0x7ffa642603c5 in mozilla::TaskController::ProcessPendingMTTask(bool) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:516:36
#44 0x7ffa6426f789 in operator() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:237:37
#45 0x7ffa6426f789 in mozilla::detail::RunnableFunction<mozilla::TaskController::TaskController()::$_1>::Run() /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.h:548:5
#46 0x7ffa642837fd in nsThread::ProcessNextEvent(bool, bool*) /builds/worker/checkouts/gecko/xpcom/threads/nsThread.cpp:1204:16
#47 0x7ffa6428a82f in NS_ProcessNextEvent(nsIThread*, bool) /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.cpp:480:10
#48 0x7ffa6628b78c in bool mozilla::SpinEventLoopUntil<(mozilla::ProcessFailureBehavior)1, nsGlobalWindowOuter::Print(nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*, nsIDocShell*, nsGlobalWindowOuter::IsPreview, nsGlobalWindowOuter::IsForWindowDotPrint, std::function<void (mozilla::dom::PrintPreviewResultInfo const&)>&&, RefPtr<mozilla::dom::BrowsingContext>*, mozilla::ErrorResult&)::$_1>(nsTSubstring<char> const&, nsGlobalWindowOuter::Print(nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*, nsIDocShell*, nsGlobalWindowOuter::IsPreview, nsGlobalWindowOuter::IsForWindowDotPrint, std::function<void (mozilla::dom::PrintPreviewResultInfo const&)>&&, RefPtr<mozilla::dom::BrowsingContext>*, mozilla::ErrorResult&)::$_1&&, nsIThread*) /builds/worker/workspace/obj-build/dist/include/mozilla/SpinEventLoopUntil.h:176:25
#49 0x7ffa66288dd3 in nsGlobalWindowOuter::Print(nsIPrintSettings*, mozilla::layout::RemotePrintJobChild*, nsIWebProgressListener*, nsIDocShell*, nsGlobalWindowOuter::IsPreview, nsGlobalWindowOuter::IsForWindowDotPrint, std::function<void (mozilla::dom::PrintPreviewResultInfo const&)>&&, RefPtr<mozilla::dom::BrowsingContext>*, mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:5252:5
#50 0x7ffa662873aa in nsGlobalWindowOuter::PrintOuter(mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowOuter.cpp:5008:3
#51 0x7ffa66240df9 in nsGlobalWindowInner::Print(mozilla::ErrorResult&) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowInner.cpp:3733:3
#52 0x7ffa672a2b3c in mozilla::dom::Window_Binding::print(JSContext*, JS::Handle<JSObject*>, void*, JSJitMethodCallArgs const&) /builds/worker/workspace/obj-build/dom/bindings/./WindowBinding.cpp:3136:24
#53 0x7ffa677a5a02 in bool mozilla::dom::binding_detail::GenericMethod<mozilla::dom::binding_detail::MaybeCrossOriginObjectThisPolicy, mozilla::dom::binding_detail::ThrowExceptions>(JSContext*, unsigned int, JS::Value*) /builds/worker/checkouts/gecko/dom/bindings/BindingUtils.cpp:3268:13
#54 0x7ffa6af5d844 in CallJSNative(JSContext*, bool (*)(JSContext*, unsigned int, JS::Value*), js::CallReason, JS::CallArgs const&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:481:13
#55 0x7ffa6af5d02f in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:575:12
#56 0x7ffa6af6d0c9 in CallFromStack /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:647:10
#57 0x7ffa6af6d0c9 in js::Interpret(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:3190:16
#58 0x7ffa6af5c776 in js::RunScript(JSContext*, js::RunState&) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:453:13
#59 0x7ffa6af5d128 in js::InternalCallOrConstruct(JSContext*, JS::CallArgs const&, js::MaybeConstruct, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:607:13
#60 0x7ffa6af5e62f in js::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, js::AnyInvokeArgs const&, JS::MutableHandle<JS::Value>, js::CallReason) /builds/worker/checkouts/gecko/js/src/vm/Interpreter.cpp:674:8
#61 0x7ffa6b069107 in JS::Call(JSContext*, JS::Handle<JS::Value>, JS::Handle<JS::Value>, JS::HandleValueArray const&, JS::MutableHandle<JS::Value>) /builds/worker/checkouts/gecko/js/src/vm/CallAndConstruct.cpp:119:10
#62 0x7ffa671984d9 in mozilla::dom::IdleRequestCallback::Call(mozilla::dom::BindingCallContext&, JS::Handle<JS::Value>, mozilla::dom::IdleDeadline&, mozilla::ErrorResult&) /builds/worker/workspace/obj-build/dom/bindings/./WindowBinding.cpp:455:8
#63 0x7ffa663446e4 in mozilla::dom::IdleRequestCallback::Call(mozilla::dom::IdleDeadline&, mozilla::ErrorResult&, char const*, mozilla::dom::CallbackObject::ExceptionHandling, JS::Realm*) /builds/worker/workspace/obj-build/dist/include/mozilla/dom/WindowBinding.h:386:12
#64 0x7ffa664fb296 in Call /builds/worker/workspace/obj-build/dist/include/mozilla/dom/WindowBinding.h:399:12
#65 0x7ffa664fb296 in mozilla::dom::IdleRequest::IdleRun(nsPIDOMWindowInner*, double, bool) /builds/worker/checkouts/gecko/dom/base/IdleRequest.cpp:57:13
#66 0x7ffa66225c11 in nsGlobalWindowInner::RunIdleRequest(mozilla::dom::IdleRequest*, double, bool) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowInner.cpp:730:12
#67 0x7ffa66224a61 in nsGlobalWindowInner::ExecuteIdleRequest(mozilla::TimeStamp) /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowInner.cpp:758:3
#68 0x7ffa662247f0 in IdleRequestExecutor::Run() /builds/worker/checkouts/gecko/dom/base/nsGlobalWindowInner.cpp:599:13
#69 0x7ffa6426bd87 in mozilla::RunnableTask::Run() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:580:16
#70 0x7ffa64261786 in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:907:26
#71 0x7ffa642600ae in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:772:15
#72 0x7ffa642603c5 in mozilla::TaskController::ProcessPendingMTTask(bool) /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:516:36
#73 0x7ffa6426f726 in operator() /builds/worker/checkouts/gecko/xpcom/threads/TaskController.cpp:234:37
#74 0x7ffa6426f726 in mozilla::detail::RunnableFunction<mozilla::TaskController::TaskController()::$_0>::Run() /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.h:548:5
#75 0x7ffa642837fd in nsThread::ProcessNextEvent(bool, bool*) /builds/worker/checkouts/gecko/xpcom/threads/nsThread.cpp:1204:16
#76 0x7ffa6428a82f in NS_ProcessNextEvent(nsIThread*, bool) /builds/worker/checkouts/gecko/xpcom/threads/nsThreadUtils.cpp:480:10
#77 0x7ffa64f31095 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:85:21
#78 0x7ffa64e485c1 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:363:3
#79 0x7ffa64e485c1 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:345:3
#80 0x7ffa69cca0c8 in nsBaseAppShell::Run() /builds/worker/checkouts/gecko/widget/nsBaseAppShell.cpp:148:27
#81 0x7ffa69d80bd8 in nsAppShell::Run() /builds/worker/checkouts/gecko/widget/gtk/nsAppShell.cpp:469:33
#82 0x7ffa6ad3789b in XRE_RunAppShell() /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:712:20
#83 0x7ffa64f31f76 in mozilla::ipc::MessagePumpForChildProcess::Run(base::MessagePump::Delegate*) /builds/worker/checkouts/gecko/ipc/glue/MessagePump.cpp:235:9
#84 0x7ffa64e485c1 in RunHandler /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:363:3
#85 0x7ffa64e485c1 in MessageLoop::Run() /builds/worker/checkouts/gecko/ipc/chromium/src/base/message_loop.cc:345:3
#86 0x7ffa6ad3712b in XRE_InitChildProcess(int, char**, XREChildData const*) /builds/worker/checkouts/gecko/toolkit/xre/nsEmbedFunctions.cpp:647:34
#87 0x563e080b0b1f in content_process_main /builds/worker/checkouts/gecko/browser/app/../../ipc/contentproc/plugin-container.cpp:57:28
#88 0x563e080b0b1f in main /builds/worker/checkouts/gecko/browser/app/nsBrowserApp.cpp:378:18
#89 0x7ffa788e9d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#90 0x7ffa788e9e3f in __libc_start_main csu/../csu/libc-start.c:392:3
#91 0x563e08086558 in _start (/home/worker/builds/m-c-20240611133415-fuzzing-debug/firefox-bin+0x58558) (BuildId: a4911e1096dc1d40081e28f640946a081f79a9cc)

Verified bug as reproducible on mozilla-central 20240613225703-32dddfc0818f.
The bug appears to have been introduced in the following build range:

Start: 7079db6b8da9081aee6b0ce96b68f368efec3277 (20240124092956)
End: ab0fef54b03d1b80d2515d42a933725cc934e6d8 (20240124112053)
Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=7079db6b8da9081aee6b0ce96b68f368efec3277&tochange=ab0fef54b03d1b80d2515d42a933725cc934e6d8

Bug 1876256 from the pushlog in Comment 1 looks like a possible regressor. Please correct if needed.

We're not going to go back to iterating through all the children to find the primary frame. We've a number of similar bugs on this assertion and none are serious.

Triaging as S3 given comment 3.

Successfully recorded a pernosco session. A link to the pernosco session will be added here shortly.

A pernosco session for this bug can be found here.

A pernosco session for this bug can be found here.