▶ TIMEOUT [expected CRASH] /workers/semantics/xhr/001.html
  │ 
  │ thread 'WebWorker for http://web-platform.test:8000/workers/semantics/xhr/001.html#' panicked at 'expected a Window scope', /home/servo/buildbot/slave/linux-rel/build/components/script/dom/bindings/global.rs:73
  │ stack backtrace:
  │    1:     0x5631fa8d1880 - sys::backtrace::tracing::imp::write::h92808652e552bec0MZt
  │    2:     0x5631fa8d46e5 - panicking::log_panic::_<closure>::closure.41184
  │    3:     0x5631fa8d4160 - panicking::log_panic::hc4038fe8a2a609d626x
  │    4:     0x5631fa8bdbe3 - sys_common::unwind::begin_unwind_inner::hd5a3cc6e3320d6b8lSs
  │    5:     0x5631f964eaef - sys_common::unwind::begin_unwind::begin_unwind::h10528527346985475295
  │    6:     0x5631f9a939f9 - dom::xmlhttprequest::_<impl>::new_doc::h3c7a40b41e9a9169mEY
  │    7:     0x5631f9a92a8c - dom::xmlhttprequest::_<impl>::handle_xml::h36b9539d653de1d2nDY
  │    8:     0x5631f98af957 - dom::xmlhttprequest::_<impl>::GetResponseXML::h99eaed5c42cbf28cfiY
  │    9:     0x5631f98af2db - dom::bindings::codegen::Bindings::XMLHttpRequestBinding::get_responseXML::h3d7d04f717088d5cGTd
  │   10:     0x5631f9fe82e6 - CallJitGetterOp
  │   11:     0x5631f968bfe7 - dom::bindings::utils::generic_call::hbcacf4900a536a849Zf
  │   12:     0x5631fa10403c - _ZN2js6InvokeEP9JSContextN2JS8CallArgsENS_14MaybeConstructE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/jscntxtinlines.h:235
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:502
  │   13:     0x5631fa10552e - _ZN2js6InvokeEP9JSContextRKN2JS5ValueES5_jPS4_NS2_13MutableHandleIS3_EE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:558
  │   14:     0x5631fa108c49 - _ZN2js20InvokeGetterOrSetterEP9JSContextP8JSObjectN2JS5ValueEjPS5_NS4_13MutableHandleIS5_EE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:628
  │   15:     0x5631fa12a0f2 - _ZL10CallGetterP9JSContextN2JS6HandleIP8JSObjectEENS2_IPN2js5ShapeEEENS1_13MutableHandleINS1_5ValueEEE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/NativeObject.cpp:1614
  │   16:     0x5631fa149e00 - _ZN2js17NativeGetPropertyEP9JSContextN2JS6HandleIPNS_12NativeObjectEEENS3_IP8JSObjectEENS3_I4jsidEENS2_13MutableHandleINS2_5ValueEEE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/NativeObject.cpp:1664
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/NativeObject.cpp:1878
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/NativeObject.cpp:1912
  │   17:     0x5631fa110908 - _ZN2js11GetPropertyEP9JSContextN2JS6HandleIP8JSObjectEES6_NS3_I4jsidEENS2_13MutableHandleINS2_5ValueEEE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/NativeObject.h:1434
  │   18:     0x5631fa0f851b - _ZL9InterpretP9JSContextRN2js8RunStateE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:260
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:2426
  │   19:     0x5631fa103d1c - _ZN2js9RunScriptEP9JSContextRNS_8RunStateE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:452
  │   20:     0x5631fa103f9d - _ZN2js6InvokeEP9JSContextN2JS8CallArgsENS_14MaybeConstructE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:521
  │   21:     0x5631fa10552e - _ZN2js6InvokeEP9JSContextRKN2JS5ValueES5_jPS4_NS2_13MutableHandleIS3_EE
  │                         at /home/servo/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/Interpreter.cpp:558
  └   22:     0x5631fa3cda39 - _Z20JS_CallFunctionValueP9JSContextN2JS6HandleIP8JSObjectEENS2_INS1_5ValueEEERKNS1_16HandleValueArrayENS1_13MutableHandleIS6_EE