fix trivial matrix computation

Revert "Reverted 10056-10059"

This reverts commit bab4ebcaa7270c3b866a8e10917c39b055ebd51a.

Fix broken GM test, reintroduce image scaling.

BUG=

Review URL: https://codereview.chromium.org/18721006

git-svn-id: http://skia.googlecode.com/svn/trunk@10066 2bbb7eff-a529-9590-31e7-b0007b416f81
20 files changed