[REG 5.4.2->5.5 beta] <select> elements don't do anything when clicked

With the Qt 5.5 beta, <select> elements don't do anything - when I click them, no menu pops up.

When downgrading to 5.4.2, it works fine.

I attached an example HTML file, but I see this everywhere where a select-element is used. It's reproducable with the example browser (and any other QtWebKit based browser).