v0.13.1

Changes

• A layout pass no longer hangs the main thread when layoutLock is already held. A UI stress test
  deadlocked the editor with the main thread blocked on a lock it owned and no layout pass beneath
  it, so an earlier pass had leaked the lock. layoutLines now tries the lock: if it is held, it
  logs a fault in the TextLayoutManager category and skips that pass instead of waiting forever.
  This is a safety net; what leaks the lock is not yet known, and the fault log is how to find out.