Topic: Firefox globalCompositeOperation

I'm trying to use some transparent PNGs and the globalCompositeOperation and came across a few instances where Firefox fails to render anything.

http://jsdo.it/kylethefeared/goKO
All of these appear to work fine in Chrome or Opera (although lighter and darker give slightly different results).

I'm actually looking to use either source-in or destination-in (either would work for my purposes).
I don't suppose there's a workaround to achieve the same thing with the various other composite operations that do work?

FYI for some obscure reasons I still fail to understand, darker was removed from the HTML5 Canvas spec months ago. Another thing I don't understand is why Webkit keep supporting this operation without a vendor prefix.

No, there's no short workaround to achieve source-in or destination-in. These operations are pretty basic, and emulating them with say a xor of the xor and source-over or destination-over would be crazy scaffolding for no reason.