differentiate mag and min filters

BUG=
R=bsalomon@google.com, robertphillips@google.com

Author: humper@google.com

Review URL: https://chromiumcodereview.appspot.com/20809002

git-svn-id: http://skia.googlecode.com/svn/trunk@10397 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed