page-break-inside: avoid; definitely does not work in webkit, in fact has been a known issue for 5+ years now https://bugs.webkit.org/show_bug.cgi?id=5097
As far as my research has gone, there is no known method to accomplish this (I am working on figuring out my own hack)
The advice I can give you is, to accomplish this functionality in FF, wrap the content that you don;t want to break ever inside a DIV (or any container) with overflow: auto (just be careful not to cause weird scroll bars to show up by sizing the container too small).
Sadly, FF is the only browser I managed to accomplish this in, and webkit is the one I am more worried about.