The Google Chrome OS

Javascript bindings don't mean squat unless you have something to accelerate them. I don't care if the game is 3D, in your browser, or full screen 2D or anything like that or outside the browser or anything like that. It's irrelevant.

A framebuffer driver is just that.. you take information and you write it out to a framebuffer. It's a memory region. It does not get you any sort of OpenGL acceleration or hardware scaling or accelerated YUV to RGB conversion or anything like that. Your worse off, efficiency-wise, with a plain FB driver then you were back in VGA graphics days.

Xorg provides a framework for 2D and 3D acceleration. It's almost always going to have better performance then a simple FB driver unless something is severely broken.

If you don't want to use Xorg then you have to replace it with something else.

Wayland is a possibility and it provides it's own 2D and 3D acceleration whatnot. But it's not mature.