▶ CRASH [expected OK] /html/semantics/embedded-content/the-iframe-element/iframe_sandbox_popups_nonescaping-2.html
  │ 
  │ VMware, Inc.
  │ softpipe
  │ 3.3 (Core Profile) Mesa 18.3.0-devel
  │ called `Result::unwrap()` on an `Err` value: ChannelClosedError (thread ScriptThread PipelineId { namespace_id: PipelineNamespaceId(1), index: PipelineIndex(1) }, at libcore/result.rs:1009)
  │ stack backtrace:
  │    0:     0x7ff7c1ccf82c - backtrace::backtrace::trace::h34a5004b5e0f1dc7
  │    1:     0x7ff7c1cceac2 - <backtrace::capture::Backtrace as core::default::Default>::default::hae829d87a5db9150
  │    2:     0x7ff7c1cceb38 - backtrace::capture::Backtrace::new::hcbbf9ea3df342ffc
  │    3:     0x7ff7bfdbc6d9 - servo::main::{{closure}}::h51ba156ea42514d5
  │    4:     0x7ff7c3163fa3 - std::panicking::rust_panic_with_hook::hd470ff3b3e7a1b18
  │                         at libstd/panicking.rs:480
  │    5:     0x7ff7c3163b09 - std::panicking::continue_panic_fmt::hf0cf39ae1e114602
  │                         at libstd/panicking.rs:390
  │    6:     0x7ff7c3163a05 - rust_begin_unwind
  │                         at libstd/panicking.rs:325
  │    7:     0x7ff7c3184bdb - core::panicking::panic_fmt::hf53111ba26d35bb0
  │                         at libcore/panicking.rs:77
  │    8:     0x7ff7c0967515 - core::result::unwrap_failed::hd7185e281c530a02
  │    9:     0x7ff7c0e03971 - script::dom::window::Window::force_reflow::h9dc7a957c127184d
  │   10:     0x7ff7c0e04321 - script::dom::window::Window::reflow::hb1e8e824ed0ab6ec
  │   11:     0x7ff7c065fc1f - script::dom::document::Document::finish_load::hdfd02881a144b980
  │   12:     0x7ff7c03d286e - script::dom::servoparser::ServoParser::do_parse_sync::h103cbdefc1365ca5
  │   13:     0x7ff7c0924630 - profile_traits::time::profile::h2e41df13ced9f34b
  │   14:     0x7ff7c03d20fe - _ZN6script3dom11servoparser11ServoParser10parse_sync17h2fbe697141d094d4E.llvm.8881560695366623043
  │   15:     0x7ff7c03d6d27 - <script::dom::servoparser::ParserContext as net_traits::FetchResponseListener>::process_response_eof::hebea44c43b87e236
  │   16:     0x7ff7c07f62fd - script::script_thread::ScriptThread::handle_msg_from_constellation::h153dc89d08fcf8df
  │   17:     0x7ff7c07ed584 - _ZN6script13script_thread12ScriptThread11handle_msgs17h86c5886b5c18963dE.llvm.8006955753221593022
  │   18:     0x7ff7c07e9961 - script::script_thread::ScriptThread::start::h07fe432678f1704e
  │   19:     0x7ff7c092b5df - std::sys_common::backtrace::__rust_begin_short_backtrace::h1b1159067313a487
  │   20:     0x7ff7c0f24375 - _ZN3std9panicking3try7do_call17hcb678480f4fc13b9E.llvm.3546835220730816629
  │   21:     0x7ff7c3175e19 - __rust_maybe_catch_panic
  │                         at libpanic_unwind/lib.rs:102
  │   22:     0x7ff7c0ca2590 - <F as alloc::boxed::FnBox<A>>::call_box::h71aa43712eb4ee44
  │   23:     0x7ff7c3160efa - <alloc::boxed::Box<(dyn alloc::boxed::FnBox<A, Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$RP$$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$::call_once::h9d1cd498499ed135
  │                         at liballoc/boxed.rs:682
  │                          - std::sys_common::thread::start_thread::ha4bfe77455e6e434
  │                         at libstd/sys_common/thread.rs:24
  │   24:     0x7ff7c314e4c5 - std::sys::unix::thread::Thread::new::thread_start::hebe133da3ea5230a
  │                         at libstd/sys/unix/thread.rs:90
  │   25:     0x7ff7bdaa5183 - start_thread
  │   26:     0x7ff7bc36c03c - clone
  │   27:                0x0 - <unknown>
  │ ERROR 2018-11-09T00:43:05Z: servo: called `Result::unwrap()` on an `Err` value: ChannelClosedError
  └ Pipeline failed in hard-fail mode.  Crashing!