First pass: skip motion search for intra-only
First pass: skip motion search for intra-only

BUG=webm:1713

Change-Id: Ibad79cf5d12aa913e8c87a31d7d2124c00958691

webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx