Small changes to the memory benchmark

Many people used the memory benchmark from my site and filed bugs for memory leaks, GC pause times and similar. Most of them got fixed over the last few months.

I made some small changes to the script today because the main benchmark window kept references to already closed windows. Now I manually delete the references. I also removed the recently closed 280slides.com page. If anybody sees problems with other pages, please tell me. I am happy to add new pages.

Everybody that is interested in memory behavior across browsers should check out recent measurements from PC Advisor. The results are getting better and better. Congratulations to Nick Nethercote and the memshrink team!