Running some trivial JS hangs WebKit

I've hit a hanging bug in our own application which turned out to be a problem in WebKit. We're running some JavaScript using the mainFrame's evaluateJavaScript function and with the combination of our website and even some trivial javascript code WebKit seems to run into some internal endless loop eating memory until its finally killed.

Switching to a different website, like google.com avoids the problem

I'm attaching a self-contained example application that reproduces the problem here. The same example compiled with Qt4.8 works fine, so this seems to be a regression in the webkit support.