jsf.js: HTMLUnit 2.9 throws an error on full body replacement test

This is clearly not a bug, but a problem in html unit. At a full page replacement test I am getting a undefined.noteType is not defined.
Now the problem here is I traced it down, and it seemed to be a timing issue. Inserting assertion checks which throw errors at the corresponding methods resolve the issue to a satisfying degree.
The errors clearly if triggered would have caused an error in the console log and in the page. Also the error is not present in html unit 2.6.
So I mark the fixes as improvement, because they will allow to run our tests.