Fix for SkMatrixConvolutionImageFilter with large borders.

Intersect the requested processing rect with the destination
bounds.

R=junov@chromium.org

Review URL: https://codereview.chromium.org/267863004

git-svn-id: http://skia.googlecode.com/svn/trunk@14543 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed