As of SERVER-42736 we no longer set a value for MozJSImplScope::MozRuntime::_thread. We use the id of _thread in MozJSImplScope::kill() however to confirm whether the thread that created the scope object and the current thread are the same. If so, we extract a kill status object from the OperationContext which is returned to the user.

SERVER-46227 will fix the "can we access the OperationContext" check so that we can return the correct "kill" error code when possible.