Intermittent crash in /dom/ranges/Range-surroundContents.html

[nox]

  ▶ CRASH [expected OK] /dom/ranges/Range-surroundContents.html
  │ 
  │ VMware, Inc.
  │ Gallium 0.4 on softpipe
  │ 3.3 (Core Profile) Mesa 12.0.1
  │ Stack trace for thread "ScriptThread PipelineId { namespace_id: PipelineNamespaceId(0), index: PipelineIndex(1) }"
  │ stack backtrace:
  │    0:     0x7ff947d8ff7d - backtrace::backtrace::trace::h16372ee7bf1517e5
  │    1:     0x7ff947d90612 - backtrace::capture::Backtrace::new::hcc43c50c4b11c693
  │    2:     0x7ff9467ad304 - servo::install_crash_handler::handler::hbd30f9f913d3e893
  │    3:     0x7ff947931813 - AsmJSFaultHandler
  │                         at /home/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/asmjs/WasmSignalHandlers.cpp:1171
  │    4:     0x7ff9448a332f - <unknown>
  │    5:     0x7ff940e120c3 - <unknown>
  │ Stack trace for thread "ScriptThread PipelineId { namespace_id: PipelineNamespaceId(0), index: PipelineIndex(1) }"
  │ stack backtrace:
  │    0:     0x7ff947d8ff7d - backtrace::backtrace::trace::h16372ee7bf1517e5
  │    1:     0x7ff947d90612 - backtrace::capture::Backtrace::new::hcc43c50c4b11c693
  │    2:     0x7ff9467ad304 - servo::install_crash_handler::handler::hbd30f9f913d3e893
  │    3:     0x7ff9442eecaf - <unknown>
  │    4:     0x7ff9467ad38f - servo::install_crash_handler::handler::hbd30f9f913d3e893
  │    5:     0x7ff947931813 - AsmJSFaultHandler
  │                         at /home/servo/.cargo/git/checkouts/mozjs-fa11ffc7d4f1cc2d/master/mozjs/js/src/asmjs/WasmSignalHandlers.cpp:1171
  │    6:     0x7ff9448a332f - <unknown>
  └    7:     0x7ff940e120c3 - <unknown>

[jdm]

Tracking this non-test-specific problem in #19937.