BUG=425
TESTED=out\release\libyuv_unittest_old --gtest_filter=*.ScaleDownBy3_*
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/45219004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1377 16f28f9a-4ce2-e073-06de-1de4eb20be90