There shouldn't be any CSS-related drawing. Full-stop. Your analogy is accidentally very accurate, because it's like looking at a car, then a pile of bicycles, and saying "how can I get from A to B". The sane person would go to an auto parts store, get the appropriate parts and build a car as we understand it. The madman would weld two bicycles together, and then complain that it wasn't intuitive to do - bicycles aren't supposed to be used for creating cars. Likewise, CSS is not for drawing shapes: it's for styling things. As you pointed out, we have canvas and SVG for drawing, plus images for things like icons.
As for the compatibility thing, you're coming at it the wrong way. Don't tell Google et al. to support yet another standard for CSS shapes. Let them spend their time implementing SVG and Canvas according to the existing spec. Inventing a new spec not only doesn't solve the problem, it actually re-introduces it.
1) I never mentioned a new spec.
2) " bicycles aren't supposed to be used for creating cars. " - exactly my point.
I think we said the same stuff - came at it from slightly different angles. I´m not advocating yet another standard. Im saying - lets make it easy enough to use the appropriate (and already existing) standards to draw - rather than be at the mercy of a seemingly prehistoric styling system. My point with google et al was - get together and agree to a way to do simple things like images - the same way across browsers.
As for the compatibility thing, you're coming at it the wrong way. Don't tell Google et al. to support yet another standard for CSS shapes. Let them spend their time implementing SVG and Canvas according to the existing spec. Inventing a new spec not only doesn't solve the problem, it actually re-introduces it.