Adding a bit of rebustness to SkRectShaderImageFilter

Since SkRectShaderImageFilter is an image filter, I added logic so that it can actually use the size of an input image as the rect if an empty rect is provided as an argument. I also added logic to prevent creating an empty device.

Review URL: https://codereview.chromium.org/14093008

git-svn-id: http://skia.googlecode.com/svn/trunk@8739 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed