I get that it's a neat hack. I really do. But this should never become standard. It just shouldn't.
I guess it beats having a videocard optimized for rendering webpages, which is probably the alternative.
Can we just clean slate reboot HTML/CSS/JavaScript to something that's quite like it but has reinvented seperation of concerns? Symantics/Syntax/Dynamics was kinda neat. Right now it's "State/Looks/Processing", and it's backwards compatible in a messy way.
I seriously think that HTML5 is just too cluttered, with no cleaning up going on. Compiling towards HTML5 is not improving the problem, and if we go down that road I suggest making languages better for compiling towards web-compatible(Hey, c, how are you? What's that? You're in browsers now?).