Documentation: using iframe may not avoid DoS

[natevw]

"Readme says you could beat while(true) with an iframe, but I think iframes share the thread." — https://twitter.com/pfrazee/status/357566263893037056

Haven't fully researched/tested but this looks like it might be the case. E.g. https://github.com/timdream/simworker uses iframes to simulate webworkers, and documentation states "The script doesn't do the magic of taking the task background. Executions still block UI…"

[dominictarr]

I just tested this, and I can confirm that in chrome iframe is the same thread.
I am now unable to open localhost:8000 because the cached script has a infinite loop in it.