BUG=none
TEST=out\release\libyuv_unittest.exe --gtest_filter=*I422ToI420*
Review URL: https://webrtc-codereview.appspot.com/1157004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@590 16f28f9a-4ce2-e073-06de-1de4eb20be90