Bricked by web app

I am developing a little webapp (standalone, installed on homescreen) for a client and the strangest thing happened.

It was working pretty good for a while and suddenly when I opened it, the statusbar wasn't rendered properly (sort of negative of what it should look like, all white with faint text), that was the first indication that something was off...

Then when I tried to return to the homescreen, IT WOULDN'T. I was locked in the webapp. So I tried locking the iPhone with the button on the top, and NOTHING happened. Then I tried shutting it off completely by holding the button on top, and NOTHING happened. I've connected it to power source, I've hooked it up to iTunes, but all to no avail, it was completely bricked.

The only thing that was still accessible was Siri (had some great fun with her). Ultimately I had no other option than to resort to a iTunes restore, which is currently in progress.

Has anyone ever experienced this? And how did you solve this.

I have to add, this is actually the second time this happened, last time was years ago on an iPhone 4S. Can't remember how I solved it then.

It should not be possible for a webapp to completely ruin an iPhone... Right? ;-)