Cleanup patch to move all of SkImageFilterUtils into SkImageFilter.

This was a utility class that dates from before GPU code was allowed
in core. Now that it is, there's no reason not to have this
functionality in SkImageFilter.

Covered by existing tests.

R=reed@google.com

Review URL: https://codereview.chromium.org/185973003

git-svn-id: http://skia.googlecode.com/svn/trunk@13646 2bbb7eff-a529-9590-31e7-b0007b416f81
12 files changed