requestFullScreen in a cross-origin frame panics

[jdm]

I observed this in https://aframe.io/examples/showcase/a-painter/ pressing the button in the bottom right corner of the demo.

No current global object (thread ScriptThread PipelineId { namespace_id: PipelineNamespaceId(1), index: PipelineIndex(1) }, at components/script/dom/window.rs:816)
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /Users/joshmatthews/.cargo/git/checkouts/backtrace-rs-96ebaf1bcb788384/91a0aa4/src/backtrace/libunwind.rs:86
      backtrace::backtrace::trace_unsynchronized
             at /Users/joshmatthews/.cargo/git/checkouts/backtrace-rs-96ebaf1bcb788384/91a0aa4/src/backtrace/mod.rs:66
   1: <servo::backtrace::Print as core::fmt::Debug>::fmt
             at ports/glutin/backtrace.rs:49
   2: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   3: std::io::Write::write_fmt
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/io/mod.rs:1504
   4: servo::backtrace::print
             at ports/glutin/backtrace.rs:17
   5: servo::main::{{closure}}
             at ports/glutin/main2.rs:157
   6: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:515
   7: rust_begin_unwind
             at src/libstd/panicking.rs:419
   8: std::panicking::begin_panic
   9: std::panicking::begin_panic
  10: core::option::Option<T>::expect
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libcore/option.rs:347
  11: <script::dom::window::Window as script::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods>::GetFrameElement
             at components/script/dom/window.rs:816
  12: script::dom::document::Document::get_allow_fullscreen
             at components/script/dom/document.rs:3404
  13: script::dom::element::Element::fullscreen_element_ready_check
             at components/script/dom/element.rs:1817
  14: <script::dom::element::ElementPerformFullscreenEnter as script::task::TaskOnce>::run_once
             at components/script/dom/element.rs:3599
  15: <T as script::task::TaskBox>::run_box
             at components/script/task.rs:57
  16: script::script_thread::ScriptThread::handle_msg_from_script
             at components/script/script_thread.rs:1944
  17: script::script_thread::ScriptThread::handle_msgs::{{closure}}
             at components/script/script_thread.rs:1550
  18: script::script_thread::ScriptThread::profile_event
             at components/script/script_thread.rs:1782
  19: script::script_thread::ScriptThread::handle_msgs
             at components/script/script_thread.rs:1543
  20: script::script_thread::ScriptThread::start
             at components/script/script_thread.rs:1378
  21: <script::script_thread::ScriptThread as script_traits::ScriptThreadFactory>::create::{{closure}}::{{closure}}
             at components/script/script_thread.rs:803
  22: profile_traits::mem::ProfilerChan::run_with_memory_reporting
             at /Users/joshmatthews/src/servo-master/components/profile_traits/mem.rs:88
  23: <script::script_thread::ScriptThread as script_traits::ScriptThreadFactory>::create::{{closure}}
             at components/script/script_thread.rs:801
  24: std::sys_common::backtrace::__rust_begin_short_backtrace
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/sys_common/backtrace.rs:130
  25: std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/thread/mod.rs:475
  26: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/panic.rs:318
  27: std::panicking::try::do_call
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/panicking.rs:331
  28: __rust_try
  29: std::panicking::try
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/panicking.rs:274
  30: std::panic::catch_unwind
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/panic.rs:394
  31: std::thread::Builder::spawn_unchecked::{{closure}}
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libstd/thread/mod.rs:474
  32: core::ops::function::FnOnce::call_once{{vtable.shim}}
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/libcore/ops/function.rs:232
  33: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/liballoc/boxed.rs:1008
  34: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/42abbd8878d3b67238f3611b0587c704ba94f39c/src/liballoc/boxed.rs:1008
      std::sys::unix::thread::Thread::new::thread_start
             at src/libstd/sys/unix/thread.rs:87
  35: <unknown>

[jdm]

Actually this may not be about cross-origin frames; the panic comes from GlobalScope::current(), which expects a script settings object on the stack that isn't present. It's a method that's being called from a task, not from a JS script, so the assumption about how to obtain the global object is being violated.