remove unused (by clients) SkUnitMapper

BUG=skia:
R=robertphillips@google.com, scroggo@google.com, george@mozilla.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/283273002

git-svn-id: http://skia.googlecode.com/svn/trunk@14761 2bbb7eff-a529-9590-31e7-b0007b416f81
48 files changed