This specific example may be new, but the concept of fooling users with websites containing images of the system's own UI is not new --- for example, all the fake antivirus alert boxes. That had a relatively easy mitigation --- using non-default appearance on your system (e.g. an XP-style "you have a virus!" dialog box image would just look silly if you weren't using XP with the default theme), but it seems the trend toward un-customisability is just going to lead to this being even more easy to exploit.
Of course, mobile browsers hiding important information and being even more un-customisable makes this worse.
Well, even I, as the creator of the inception bar, found myself accidentally using it!
When reading a product's documentation that has screenshots explaining how to do something, I've also accidentally tried to manipulate them instead of the actual dialogs. I'm sure others here have had similar experiences too.