backtraces

GC overwriting rooted JSObject pointer:
(gdb) bt
#0  0x000055555881ca67 in mozilla::PodSet<jsval_layout> (aDst=0x2aaac2005080, aSrc=..., aNElem=4)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsutil.h:312
#1  0x00005555587de5f6 in Poison (ptr=0x2aaac2005080, value=75 'K', num=32)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsutil.h:369
#2  0x00005555588480a4 in js::gc::Arena::finalize<JSObject> (this=0x2aaac2005000, fop=0x2aaabfb116c0, thingKind=js::gc::AllocKind::OBJECT0_BACKGROUND, 
    thingSize=32) at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:448
#3  0x000055555881d344 in FinalizeTypedArenas<JSObject> (fop=0x2aaabfb116c0, src=0x2aaabfb10570, dest=..., thingKind=js::gc::AllocKind::OBJECT0_BACKGROUND, 
    budget=..., keepArenas=js::gc::ArenaLists::KEEP_ARENAS) at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:505
#4  0x00005555587e9c46 in FinalizeArenas (fop=0x2aaabfb116c0, src=0x2aaabfb10570, dest=..., thingKind=js::gc::AllocKind::OBJECT0_BACKGROUND, budget=..., 
    keepArenas=js::gc::ArenaLists::KEEP_ARENAS) at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:539
#5  0x00005555587f131b in js::gc::ArenaLists::backgroundFinalize (fop=0x2aaabfb116c0, listHead=0x0, empty=0x2aaabfb11648)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:2789
#6  0x00005555587f2aa3 in js::gc::GCRuntime::sweepBackgroundThings (this=0x2aaac17927c8, zones=..., freeBlocks=..., threadType=js::BackgroundThread)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:3197
#7  0x00005555587f392a in js::GCHelperState::doSweep (this=0x2aaac1794d78, lock=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:3423
#8  0x00005555587f32b3 in js::GCHelperState::work (this=0x2aaac1794d78)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:3325
#9  0x00005555589d2d14 in js::HelperThread::handleGCHelperWorkload (this=0x2aaab33aa200)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/vm/HelperThreads.cpp:1672
#10 0x00005555589d301b in js::HelperThread::threadLoop (this=0x2aaab33aa200)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/vm/HelperThreads.cpp:1736
#11 0x00005555589d17e1 in js::HelperThread::ThreadMain (arg=0x2aaab33aa200)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/vm/HelperThreads.cpp:1347
#12 0x0000555558a3becb in nspr::Thread::ThreadRoutine (arg=0x2aaab63ff120)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/vm/PosixNSPR.cpp:45
#13 0x00002aaaaaed1934 in thread_trampoline (arg=0x2aaab5de1f80) at /home/jdm/rr-toplevel/rr/src/preload/preload.c:655
#14 0x00002aaaaccbd182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#15 0x00002aaaad1e347d in clone () from /lib/x86_64-linux-gnu/libc.so.6

Allocation that triggers GC (backtrace from same point in time as previous backtrace, original thread):
(gdb) bt
#0  0x00002aaaaccc1414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x0000555558d7ac8e in js::ConditionVariable::wait (this=0x2aaac1794d80, lock=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/threading/posix/ConditionVariable.cpp:117
#2  0x00005555587f312c in js::GCHelperState::waitForBackgroundThread (this=0x2aaac1794d78, lock=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:3299
#3  0x00005555587f37dc in js::GCHelperState::waitBackgroundSweepEnd (this=0x2aaac1794d78)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:3401
#4  0x00005555583ef910 in js::gc::GCRuntime::waitBackgroundSweepEnd (this=0x2aaac17927c8)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/gc/GCRuntime.h:677
#5  0x00005555587fcb0e in js::gc::GCRuntime::incrementalCollectSlice (this=0x2aaac17927c8, budget=..., reason=JS::gcreason::DEBUG_GC, lock=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:5975
#6  0x00005555587fd4f1 in js::gc::GCRuntime::gcCycle (this=0x2aaac17927c8, nonincrementalByAPI=true, budget=..., reason=JS::gcreason::DEBUG_GC)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:6174
#7  0x00005555587fda9a in js::gc::GCRuntime::collect (this=0x2aaac17927c8, nonincrementalByAPI=true, budget=..., reason=JS::gcreason::DEBUG_GC)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:6287
#8  0x00005555587fde60 in js::gc::GCRuntime::gc (this=0x2aaac17927c8, gckind=GC_NORMAL, reason=JS::gcreason::DEBUG_GC)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:6354
#9  0x00005555587ffe23 in js::gc::GCRuntime::runDebugGC (this=0x2aaac17927c8)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsgc.cpp:6842
#10 0x0000555558c8734d in js::gc::GCRuntime::gcIfNeededPerAllocation (this=0x2aaac17927c8, cx=0x2aaac17921c0)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/gc/Allocator.cpp:225
#11 0x0000555558c9185e in js::gc::GCRuntime::checkAllocatorState<(js::AllowGC)1> (this=0x2aaac17927c8, cx=0x2aaac17921c0, kind=js::gc::AllocKind::FIRST)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/gc/Allocator.cpp:190
#12 0x0000555558c8e9f6 in js::Allocate<JSObject, (js::AllowGC)1> (cx=0x2aaac17921c0, kind=js::gc::AllocKind::FIRST, nDynamicSlots=0, 
    heap=js::gc::TenuredHeap, clasp=0x55555c8a0960 <JSFunction::class_>)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/gc/Allocator.cpp:47
#13 0x000055555882ebb3 in JSObject::create (cx=0x2aaac17921c0, kind=js::gc::AllocKind::FIRST, heap=js::gc::TenuredHeap, shape=..., group=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobjinlines.h:352
#14 0x000055555880e49a in NewObject (cx=0x2aaac17921c0, group=..., kind=js::gc::AllocKind::FIRST, newKind=js::SingletonObject, initialShapeFlags=0)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:671
#15 0x000055555880edd0 in js::NewObjectWithClassProtoCommon (cxArg=0x2aaac17921c0, clasp=0x55555c8a0960 <JSFunction::class_>, protoArg=..., 
    allocKind=js::gc::AllocKind::FIRST, newKind=js::SingletonObject)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:799
#16 0x000055555840d485 in js::NewObjectWithClassProto (cx=0x2aaac17921c0, clasp=0x55555c8a0960 <JSFunction::class_>, proto=..., 
    allocKind=js::gc::AllocKind::FIRST, newKind=js::SingletonObject)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobjinlines.h:703
#17 0x00005555587e7cb6 in js::NewFunctionWithProto (cx=0x2aaac17921c0, native=0x5555575cad50 <script::dom::bindings::utils::generic_method>, nargs=2, 
    flags=JSFunction::NATIVE_FUN, enclosingDynamicScope=..., atom=..., proto=..., allocKind=js::gc::AllocKind::FIRST, newKind=js::SingletonObject, 
    protoHandling=js::NewFunctionClassProto) at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsfun.cpp:2136
#18 0x00005555587e7883 in js::NewNativeFunction (cx=0x2aaac17921c0, native=0x5555575cad50 <script::dom::bindings::utils::generic_method>, nargs=2, atom=..., 
    allocKind=js::gc::AllocKind::FIRST, newKind=js::GenericObject)
---Type <return> to continue, or q <return> to quit---
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsfun.cpp:2072
#19 0x0000555558743560 in JS::NewFunctionFromSpec (cx=0x2aaac17921c0, fs=0x55555c766570 <ref91075>, id=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsapi.cpp:3394
#20 0x0000555558818189 in DefineFunctionFromSpec (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>, flags=1, intrinsic=js::NotIntrinsic)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2943
#21 0x00005555588182ab in js::DefineFunctions (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>, intrinsic=js::NotIntrinsic)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2959
#22 0x00005555587442d6 in JS_DefineFunctions (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsapi.cpp:3625
#23 0x00005555583516f4 in js::rust::define_methods (cx=0x2aaac17921c0, obj=..., methods=...)
    at /home/jdm/servo/./.cargo/git/checkouts/rust-mozjs-8611526964119dd6/master/src/rust.rs:960
#24 0x000055555754f88c in script::dom::bindings::interface::define_guarded_methods (cx=0x2aaac17921c0, obj=..., methods=...)
    at /home/jdm/servo/components/script/dom/bindings/interface.rs:295
#25 0x000055555754f516 in script::dom::bindings::interface::create_object (cx=0x2aaac17921c0, proto=..., 
    class=0x55555c766510 <script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::PrototypeClass::h503ef0f273e81249>, methods=..., 
    properties=..., constants=..., rval=...) at /home/jdm/servo/components/script/dom/bindings/interface.rs:271
#26 0x000055555754e62d in script::dom::bindings::interface::create_interface_prototype_object (cx=0x2aaac17921c0, proto=..., 
    class=0x55555c766510 <script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::PrototypeClass::h503ef0f273e81249>, 
    regular_methods=..., regular_properties=..., constants=..., unscopable_names=..., rval=...)
    at /home/jdm/servo/components/script/dom/bindings/interface.rs:186
#27 0x0000555557b2300b in script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::CreateInterfaceObjects (cx=0x2aaac17921c0, 
    global=..., cache=0x2aaab6be7800) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#28 0x0000555557b2262d in script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::GetProtoObject (cx=0x2aaac17921c0, global=..., 
    rval=...) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#29 0x0000555557c983ca in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::CreateInterfaceObjects (cx=0x2aaac17921c0, global=..., 
    cache=0x2aaab6be7800) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#30 0x0000555557c9061d in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::GetProtoObject (cx=0x2aaac17921c0, global=..., rval=...)
    at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#31 0x0000555557c97a79 in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::Wrap (cx=0x2aaac17921c0, object=0x2aaab4fab800)
    at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#32 0x0000555557a18da2 in script::dom::window::{{impl}}::new (runtime=..., script_chan=..., dom_task_source=..., user_task_source=..., 
    network_task_source=..., history_task_source=..., file_task_source=..., image_cache_chan=..., image_cache_thread=..., resource_threads=..., 
    bluetooth_thread=..., mem_profiler_chan=..., time_profiler_chan=..., devtools_chan=..., constellation_chan=..., control_chan=..., scheduler_chan=..., 
    timer_event_chan=..., layout_chan=..., id=..., parent_info=..., window_size=...) at /home/jdm/servo/components/script/dom/window.rs:1738
#33 0x0000555557a66569 in script::script_thread::{{impl}}::load (self=0x2aaabea0d0b0, metadata=..., incomplete=...)
    at /home/jdm/servo/components/script/script_thread.rs:1594
#34 0x0000555557d43d4d in script::script_thread::{{impl}}::handle_page_headers_available::{{closure}} (meta=...)
    at /home/jdm/servo/components/script/script_thread.rs:1424
#35 0x00005555569d2d30 in core::option::{{impl}}::map<net_traits::Metadata,script::parse::ParserRoot,closure> (self=..., f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libcore/option.rs:385
#36 0x0000555557a62de3 in script::script_thread::{{impl}}::handle_page_headers_available (self=0x2aaabea0d0b0, id=0x2aaab74bf404, metadata=...)
---Type <return> to continue, or q <return> to quit---
    at /home/jdm/servo/components/script/script_thread.rs:1424
#37 0x0000555557d69948 in script::script_thread::{{impl}}::page_headers_available::{{closure}} (root=0x2aaabea10360)
    at /home/jdm/servo/components/script/script_thread.rs:494
#38 0x0000555556ed7434 in std::thread::local::{{impl}}::with<core::cell::Cell<core::option::Option<*const script::script_thread::ScriptThread>>,closure,core::option::Option<script::parse::ParserRoot>> (self=0x55555c7b4a78 <script::script_thread::SCRIPT_THREAD_ROOT::h05f477d515d29de9>, f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/local.rs:245
#39 0x0000555557a4f6f6 in script::script_thread::{{impl}}::page_headers_available (id=0x2aaab74bf404, metadata=...)
    at /home/jdm/servo/components/script/script_thread.rs:492
#40 0x00005555579b932f in script::dom::servohtmlparser::{{impl}}::headers_available (self=0x2aaab74bf3e0, meta_result=...)
    at /home/jdm/servo/components/script/dom/servohtmlparser.rs:101
#41 0x000055555732187d in net_traits::{{impl}}::process<script::dom::servohtmlparser::ParserContext> (self=..., listener=0x2aaab74bf3e0)
    at /home/jdm/servo/components/net_traits/lib.rs:287
#42 0x0000555557a3e3b6 in script::network_listener::{{impl}}::handler<net_traits::ResponseAction,script::dom::servohtmlparser::ParserContext> (
    self=0x2aaab63d0d00) at /home/jdm/servo/components/script/network_listener.rs:71
#43 0x0000555557a56fed in script::script_thread::{{impl}}::handle_msg_from_script (self=0x2aaabea0d0b0, msg=...)
    at /home/jdm/servo/components/script/script_thread.rs:951
#44 0x0000555557d36ded in script::script_thread::{{impl}}::handle_msgs::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:785
#45 0x0000555557a55a07 in script::script_thread::{{impl}}::profile_event<closure,core::option::Option<bool>> (self=0x2aaabea0d0b0, category=NetworkEvent, 
    f=...) at /home/jdm/servo/components/script/script_thread.rs:879
#46 0x0000555557a532d1 in script::script_thread::{{impl}}::handle_msgs (self=0x2aaabea0d0b0) at /home/jdm/servo/components/script/script_thread.rs:777
#47 0x0000555557a518bd in script::script_thread::{{impl}}::start (self=0x2aaabea0d0b0) at /home/jdm/servo/components/script/script_thread.rs:631
#48 0x0000555557d36005 in script::script_thread::{{impl}}::create::{{closure}}::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:477
#49 0x000055555688be5a in profile_traits::mem::{{impl}}::run_with_memory_reporting<closure,fn(profile_traits::mem::ReportsChan) -> script::script_runtime::CommonScriptMsg,script::script_runtime::CommonScriptMsg,std::sync::mpsc::Sender<script::script_thread::MainThreadScriptMsg>> (self=0x2aaabea0d2d0, f=..., 
    reporter_name=..., channel_for_reporter=..., msg=0x20) at /home/jdm/servo/components/profile_traits/mem.rs:59
#50 0x0000555557ef7ac7 in script::script_thread::{{impl}}::create::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:476
#51 0x00005555574546ab in std::panic::{{impl}}::call_once<(),closure> (self=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:255
#52 0x0000555556d51f4d in std::panicking::try::do_call<std::panic::AssertUnwindSafe<closure>,()> (data=0x2aaabea0e678 "")
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:356
#53 0x000055555abfbc97 in __rust_maybe_catch_panic ()
#54 0x0000555556ca5155 in std::panicking::try<(),std::panic::AssertUnwindSafe<closure>> (f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:332
#55 0x0000555556ac7b00 in std::panic::catch_unwind<std::panic::AssertUnwindSafe<closure>,()> (f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:311
#56 0x0000555557d54cc2 in std::thread::{{impl}}::spawn::{{closure}}<closure,()> ()
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/mod.rs:277
#57 0x00005555571ada0a in alloc::boxed::{{impl}}::call_box<(),closure> (self=0x2aaab4fdaa00, args=0)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/liballoc/boxed.rs:591
#58 0x000055555abf1951 in std::sys::thread::Thread::new::thread_start::h022e3887023c6290 ()
#59 0x00002aaaaaed1934 in thread_trampoline (arg=0x2aaab5df1850) at /home/jdm/rr-toplevel/rr/src/preload/preload.c:655
---Type <return> to continue, or q <return> to quit---
#60 0x00002aaaaccbd182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#61 0x00002aaaad1e347d in clone () from /lib/x86_64-linux-gnu/libc.so.6

crash:
(gdb) bt
#0  0x000055555837b396 in js::ObjectGroup::clasp (this=0xfffe4b4b4b4b4b4b)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/vm/ObjectGroup.h:95
#1  0x000055555837c1e5 in JSObject::getClass (this=0x2aaac2005080)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.h:122
#2  0x000055555882875a in JSObject::getOpsDefineProperty (this=0x2aaac2005080)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.h:132
#3  0x0000555558817270 in js::DefineProperty (cx=0x2aaac17921c0, obj=..., id=..., value=..., getter=0x0, setter=0x0, attrs=1, result=...)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2708
#4  0x0000555558817579 in js::DefineProperty (cx=0x2aaac17921c0, obj=..., id=..., value=..., getter=0x0, setter=0x0, attrs=1)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2744
#5  0x0000555558818247 in DefineFunctionFromSpec (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>, flags=1, intrinsic=js::NotIntrinsic)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2951
#6  0x00005555588182ab in js::DefineFunctions (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>, intrinsic=js::NotIntrinsic)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsobj.cpp:2959
#7  0x00005555587442d6 in JS_DefineFunctions (cx=0x2aaac17921c0, obj=..., fs=0x55555c766570 <ref91075>)
    at /home/jdm/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/jsapi.cpp:3625
#8  0x00005555583516f4 in js::rust::define_methods (cx=0x2aaac17921c0, obj=..., methods=...)
    at /home/jdm/servo/./.cargo/git/checkouts/rust-mozjs-8611526964119dd6/master/src/rust.rs:960
#9  0x000055555754f88c in script::dom::bindings::interface::define_guarded_methods (cx=0x2aaac17921c0, obj=..., methods=...)
    at /home/jdm/servo/components/script/dom/bindings/interface.rs:295
#10 0x000055555754f516 in script::dom::bindings::interface::create_object (cx=0x2aaac17921c0, proto=..., 
    class=0x55555c766510 <script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::PrototypeClass::h503ef0f273e81249>, methods=..., 
    properties=..., constants=..., rval=...) at /home/jdm/servo/components/script/dom/bindings/interface.rs:271
#11 0x000055555754e62d in script::dom::bindings::interface::create_interface_prototype_object (cx=0x2aaac17921c0, proto=..., 
    class=0x55555c766510 <script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::PrototypeClass::h503ef0f273e81249>, 
    regular_methods=..., regular_properties=..., constants=..., unscopable_names=..., rval=...)
    at /home/jdm/servo/components/script/dom/bindings/interface.rs:186
#12 0x0000555557b2300b in script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::CreateInterfaceObjects (cx=0x2aaac17921c0, 
    global=..., cache=0x2aaab6be7800) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#13 0x0000555557b2262d in script::dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetBinding::GetProtoObject (cx=0x2aaac17921c0, global=..., 
    rval=...) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#14 0x0000555557c983ca in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::CreateInterfaceObjects (cx=0x2aaac17921c0, global=..., 
    cache=0x2aaab6be7800) at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#15 0x0000555557c9061d in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::GetProtoObject (cx=0x2aaac17921c0, global=..., rval=...)
    at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#16 0x0000555557c97a79 in script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::Wrap (cx=0x2aaac17921c0, object=0x2aaab4fab800)
    at /home/jdm/servo/components/script/dom/bindings/mod.rs:161
#17 0x0000555557a18da2 in script::dom::window::{{impl}}::new (runtime=..., script_chan=..., dom_task_source=..., user_task_source=..., 
    network_task_source=..., history_task_source=..., file_task_source=..., image_cache_chan=..., image_cache_thread=..., resource_threads=..., 
    bluetooth_thread=..., mem_profiler_chan=..., time_profiler_chan=..., devtools_chan=..., constellation_chan=..., control_chan=..., scheduler_chan=..., 
    timer_event_chan=..., layout_chan=..., id=..., parent_info=..., window_size=...) at /home/jdm/servo/components/script/dom/window.rs:1738
---Type <return> to continue, or q <return> to quit---
#18 0x0000555557a66569 in script::script_thread::{{impl}}::load (self=0x2aaabea0d0b0, metadata=..., incomplete=...)
    at /home/jdm/servo/components/script/script_thread.rs:1594
#19 0x0000555557d43d4d in script::script_thread::{{impl}}::handle_page_headers_available::{{closure}} (meta=...)
    at /home/jdm/servo/components/script/script_thread.rs:1424
#20 0x00005555569d2d30 in core::option::{{impl}}::map<net_traits::Metadata,script::parse::ParserRoot,closure> (self=..., f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libcore/option.rs:385
#21 0x0000555557a62de3 in script::script_thread::{{impl}}::handle_page_headers_available (self=0x2aaabea0d0b0, id=0x2aaab74bf404, metadata=...)
    at /home/jdm/servo/components/script/script_thread.rs:1424
#22 0x0000555557d69948 in script::script_thread::{{impl}}::page_headers_available::{{closure}} (root=0x2aaabea10360)
    at /home/jdm/servo/components/script/script_thread.rs:494
#23 0x0000555556ed7434 in std::thread::local::{{impl}}::with<core::cell::Cell<core::option::Option<*const script::script_thread::ScriptThread>>,closure,core::option::Option<script::parse::ParserRoot>> (self=0x55555c7b4a78 <script::script_thread::SCRIPT_THREAD_ROOT::h05f477d515d29de9>, f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/local.rs:245
#24 0x0000555557a4f6f6 in script::script_thread::{{impl}}::page_headers_available (id=0x2aaab74bf404, metadata=...)
    at /home/jdm/servo/components/script/script_thread.rs:492
#25 0x00005555579b932f in script::dom::servohtmlparser::{{impl}}::headers_available (self=0x2aaab74bf3e0, meta_result=...)
    at /home/jdm/servo/components/script/dom/servohtmlparser.rs:101
#26 0x000055555732187d in net_traits::{{impl}}::process<script::dom::servohtmlparser::ParserContext> (self=..., listener=0x2aaab74bf3e0)
    at /home/jdm/servo/components/net_traits/lib.rs:287
#27 0x0000555557a3e3b6 in script::network_listener::{{impl}}::handler<net_traits::ResponseAction,script::dom::servohtmlparser::ParserContext> (
    self=0x2aaab63d0d00) at /home/jdm/servo/components/script/network_listener.rs:71
#28 0x0000555557a56fed in script::script_thread::{{impl}}::handle_msg_from_script (self=0x2aaabea0d0b0, msg=...)
    at /home/jdm/servo/components/script/script_thread.rs:951
#29 0x0000555557d36ded in script::script_thread::{{impl}}::handle_msgs::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:785
#30 0x0000555557a55a07 in script::script_thread::{{impl}}::profile_event<closure,core::option::Option<bool>> (self=0x2aaabea0d0b0, category=NetworkEvent, 
    f=...) at /home/jdm/servo/components/script/script_thread.rs:879
#31 0x0000555557a532d1 in script::script_thread::{{impl}}::handle_msgs (self=0x2aaabea0d0b0) at /home/jdm/servo/components/script/script_thread.rs:777
#32 0x0000555557a518bd in script::script_thread::{{impl}}::start (self=0x2aaabea0d0b0) at /home/jdm/servo/components/script/script_thread.rs:631
#33 0x0000555557d36005 in script::script_thread::{{impl}}::create::{{closure}}::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:477
#34 0x000055555688be5a in profile_traits::mem::{{impl}}::run_with_memory_reporting<closure,fn(profile_traits::mem::ReportsChan) -> script::script_runtime::CommonScriptMsg,script::script_runtime::CommonScriptMsg,std::sync::mpsc::Sender<script::script_thread::MainThreadScriptMsg>> (self=0x2aaabea0d2d0, f=..., 
    reporter_name=..., channel_for_reporter=..., msg=0x20) at /home/jdm/servo/components/profile_traits/mem.rs:59
#35 0x0000555557ef7ac7 in script::script_thread::{{impl}}::create::{{closure}} () at /home/jdm/servo/components/script/script_thread.rs:476
#36 0x00005555574546ab in std::panic::{{impl}}::call_once<(),closure> (self=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:255
#37 0x0000555556d51f4d in std::panicking::try::do_call<std::panic::AssertUnwindSafe<closure>,()> (data=0x2aaabea0e678 "")
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:356
#38 0x000055555abfbc97 in __rust_maybe_catch_panic ()
#39 0x0000555556ca5155 in std::panicking::try<(),std::panic::AssertUnwindSafe<closure>> (f=...)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:332
#40 0x0000555556ac7b00 in std::panic::catch_unwind<std::panic::AssertUnwindSafe<closure>,()> (f=...)
---Type <return> to continue, or q <return> to quit---
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:311
#41 0x0000555557d54cc2 in std::thread::{{impl}}::spawn::{{closure}}<closure,()> ()
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/mod.rs:277
#42 0x00005555571ada0a in alloc::boxed::{{impl}}::call_box<(),closure> (self=0x2aaab4fdaa00, args=0)
    at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/liballoc/boxed.rs:591
#43 0x000055555abf1951 in std::sys::thread::Thread::new::thread_start::h022e3887023c6290 ()
#44 0x00002aaaaaed1934 in thread_trampoline (arg=0x2aaab5df1850) at /home/jdm/rr-toplevel/rr/src/preload/preload.c:655
#45 0x00002aaaaccbd182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#46 0x00002aaaad1e347d in clone () from /lib/x86_64-linux-gnu/libc.so.6