Oops. I think this was just a typo while doing some work on the debugger breakpoints. Try extracting the eveng.js file in this zip over the existing one at <install>\exporters\html5\, restarting C2 and seeing if it's fixed:
I probably won't be able to release an update until Monday, but until then hopefully this will sort it out. If not it's probably something deeper and I'll have to look more carefully.