Protect filter_texture() against render target change.
Fix blend filters when input textures are "sloppy" (approx scratch texture match)
Add a new test case to gm/imagefiltersgraph, and reduce its size.

NOTE:  this will require new baselines for the imagefiltersgraph GM.

BUG=950

Review URL: https://codereview.appspot.com/6769043

git-svn-id: http://skia.googlecode.com/svn/trunk@6073 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed