Reduced with m-c:
BuildID=20190527141836
SourceStamp=944c410b7e9185a0cb90a4fbc0970299f1ff3e2b

==75824==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000048 (pc 0x7f90d7eeddab bp 0x7ffe578c7ee0 sp 0x7ffe578c7c40 T0)
==75824==The signal is caused by a READ memory access.
==75824==Hint: address points to the zero page.
    #0 0x7f90d7eeddaa in mozilla::ReflowInput::InitConstraints(nsPresContext*, mozilla::Maybe<mozilla::LogicalSize> const&, nsMargin const*, nsMargin const*, mozilla::LayoutFrameType) src/layout/generic/ReflowInput.cpp:2266:17
    #1 0x7f90d7ee4b32 in mozilla::ReflowInput::Init(nsPresContext*, mozilla::Maybe<mozilla::LogicalSize> const&, nsMargin const*, nsMargin const*) src/layout/generic/ReflowInput.cpp:380:3
    #2 0x7f90d84e3889 in nsTableWrapperFrame::InitChildReflowInput(nsPresContext&, mozilla::ReflowInput const&, mozilla::ReflowInput&) src/layout/tables/nsTableWrapperFrame.cpp:257:16
    #3 0x7f90d84e8f18 in nsTableWrapperFrame::OuterBeginReflowChild(nsPresContext*, nsIFrame*, mozilla::ReflowInput const&, mozilla::Maybe<mozilla::ReflowInput>&, int) src/layout/tables/nsTableWrapperFrame.cpp:742:3
    #4 0x7f90d84ea03a in nsTableWrapperFrame::Reflow(nsPresContext*, mozilla::ReflowOutput&, mozilla::ReflowInput const&, nsReflowStatus&) src/layout/tables/nsTableWrapperFrame.cpp:831:5
    #5 0x7f90d7c70e8f in mozilla::PresShell::DoReflow(nsIFrame*, bool, mozilla::OverflowChangedTracker*) src/layout/base/PresShell.cpp:9252:11
    #6 0x7f90d7c920b0 in mozilla::PresShell::ProcessReflowCommands(bool) src/layout/base/PresShell.cpp:9422:24
    #7 0x7f90d7c8f1c0 in mozilla::PresShell::DoFlushPendingNotifications(mozilla::ChangesToFlush) src/layout/base/PresShell.cpp:4231:11
    #8 0x7f90d7bf443a in FlushPendingNotifications src/obj-firefox/dist/include/mozilla/PresShell.h:1453:5
    #9 0x7f90d7bf443a in nsRefreshDriver::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:1979
    #10 0x7f90d7c098c9 in TickDriver src/layout/base/nsRefreshDriver.cpp:349:13
    #11 0x7f90d7c098c9 in mozilla::RefreshDriverTimer::TickRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsTArray<RefPtr<nsRefreshDriver> >&) src/layout/base/nsRefreshDriver.cpp:326
    #12 0x7f90d7c09162 in mozilla::RefreshDriverTimer::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:343:5
    #13 0x7f90d7c0d69f in RunRefreshDrivers src/layout/base/nsRefreshDriver.cpp:789:5
    #14 0x7f90d7c0d69f in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::TickRefreshDriver(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) src/layout/base/nsRefreshDriver.cpp:709
    #15 0x7f90d7c0c6f3 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyVsync(mozilla::VsyncEvent const&) src/layout/base/nsRefreshDriver.cpp:604:9
    #16 0x7f90d8781985 in mozilla::layout::VsyncChild::RecvNotify(mozilla::VsyncEvent const&) src/layout/ipc/VsyncChild.cpp:65:16
    #17 0x7f90cec4c2a4 in mozilla::layout::PVsyncChild::OnMessageReceived(IPC::Message const&) src/obj-firefox/ipc/ipdl/PVsyncChild.cpp:187:54
    #18 0x7f90ce7cdcf5 in mozilla::ipc::PBackgroundChild::OnMessageReceived(IPC::Message const&) src/obj-firefox/ipc/ipdl/PBackgroundChild.cpp:4717:32
    #19 0x7f90ce002a26 in mozilla::ipc::MessageChannel::DispatchAsyncMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message const&) src/ipc/glue/MessageChannel.cpp:2158:25
    #20 0x7f90cdffe43b in mozilla::ipc::MessageChannel::DispatchMessage(IPC::Message&&) src/ipc/glue/MessageChannel.cpp:2082:9
    #21 0x7f90ce0009f7 in mozilla::ipc::MessageChannel::RunMessage(mozilla::ipc::MessageChannel::MessageTask&) src/ipc/glue/MessageChannel.cpp:1939:3
    #22 0x7f90ce001787 in mozilla::ipc::MessageChannel::MessageTask::Run() src/ipc/glue/MessageChannel.cpp:1970:13
    #23 0x7f90ccc2f517 in nsThread::ProcessNextEvent(bool, bool*) src/xpcom/threads/nsThread.cpp:1176:14
    #24 0x7f90ccc37154 in NS_ProcessNextEvent(nsIThread*, bool) src/xpcom/threads/nsThreadUtils.cpp:486:10
    #25 0x7f90ce00be3f in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) src/ipc/glue/MessagePump.cpp:88:21
    #26 0x7f90cdee437e in RunInternal src/ipc/chromium/src/base/message_loop.cc:315:10
    #27 0x7f90cdee437e in RunHandler src/ipc/chromium/src/base/message_loop.cc:308
    #28 0x7f90cdee437e in MessageLoop::Run() src/ipc/chromium/src/base/message_loop.cc:290
    #29 0x7f90d7511733 in nsBaseAppShell::Run() src/widget/nsBaseAppShell.cpp:137:27
    #30 0x7f90dbb3584e in XRE_RunAppShell() src/toolkit/xre/nsEmbedFunctions.cpp:911:20
    #31 0x7f90cdee437e in RunInternal src/ipc/chromium/src/base/message_loop.cc:315:10
    #32 0x7f90cdee437e in RunHandler src/ipc/chromium/src/base/message_loop.cc:308
    #33 0x7f90cdee437e in MessageLoop::Run() src/ipc/chromium/src/base/message_loop.cc:290
    #34 0x7f90dbb349bc in XRE_InitChildProcess(int, char**, XREChildData const*) src/toolkit/xre/nsEmbedFunctions.cpp:749:34
    #35 0x55bfaf7b272e in content_process_main src/browser/app/../../ipc/contentproc/plugin-container.cpp:56:28
    #36 0x55bfaf7b272e in main src/browser/app/nsBrowserApp.cpp:263

The test contains contain: strict and an inline-table. I think this duplicates bug 1555757.

Thanks! Agreed that this is a dupe. I suspected bug 1555757 should be reproducible with normal (non-MathML) tables, but hadn't been able to construct a testcase for that scenario yet.