Since the nat branch landed, non-smoothed bitmap rendering is broken. See the non-smoothed-bitmap-ref-item1 reftest, which should show an image with sharp edges on the left and one with blurry edges on the right. I tried fixing this once, but don't really know why it's not working. Shouldn't be too hard to fix, though: I think the flag is correctly processed and transferred to GFX, so the bug is probably in setting it on the canvas context.