Bug:27534946
Mapping empty rects still must be done to get correct positions for
line/point rects describing strokable bounds.
Change-Id: I2f9efe543e58eb438b755276585491c1256d6719
bug:27381362
Also rejects ops with empty clip at record time, and short circuits clip
intersection, when one is empty.
Change-Id: I842612da14ad8fd9f1ba5e9e4fd027ba4e08d365