Changeset [a337bc28f9a2eebc0a34effb839d6cda5e1a35f6] by Alexander Ljungberg

Reduce number of divs used by typical apps.

Without this optimisation nil or 0x0 sized image slices in three part and nine part images result in useless empty divs.

Eliminating these divs should improve performance and reduce memory usage.

Although exact memory usage is hard to measure, in a large app the number of divs on screen went from 1012 to 984, a reduction of about 2.7%.
https://github.com/cappuccino/cappuccino/commit/a337bc28f9a2eebc0a3...