For https://github.com/servo/servo/issues/4362. This is a simple fix that avoids redesigning task_state. This doesn't track nesting depth, but it wasn't clear what would use the nesting depth if we tracked it. Maybe this is enough. Source-Repo: https://github.com/servo/servo Source-Revision: 59b9d14ca44d96b90fa812c1dfff6904c9b38dc2