The new background-break property should at least be implemented for inlines. Implementing it for pages and columns should wait until we have actual splittable boxes for those objects.
http://www.w3.org/TR/css3-background/#the-box-decoration-break
<rdar://problem/10218265>
This seems to have moved to http://www.w3.org/TR/css3-break/#box-decoration-break
Long ago implemented; let's handle the unprefixing in a new/different issue.