We often rgn-diff an area >= the other rgn. now we detect that and return empty
We do this when we update our devices in SkCanvas.cpp
Review URL: https://codereview.appspot.com/6249073

git-svn-id: http://skia.googlecode.com/svn/trunk@4101 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed