Use GL_NEAREST when doing untransformed rendering
Use GL_NEAREST when doing untransformed rendering

GL_LINEAR filtering introduces subtle artifacts compared
to pixel-exact GL_NEAREST filtering.  When the rendered
quad is un-transformed and texels will map directly to
pixels, use GL_NEAREST texture filtering to avoid such
artifacts.

BUG=none
TEST=Logged in to Chrome OS, used overview mode, verified everything still looked right.  Started chromeos-wm on bare X server with root weave, verified pixels didn't shift around anymore.

Change-Id: I7ad07797c6382d6c57ae6c2dad44b4c815fb2453

Review URL: http://codereview.chromium.org/5839001
Patch from James Jones <jajones@nvidia.com>.

joshfire/chromiumos-platform-window_manager,joshfire/chromiumos-platform-window_manager,joshfire/chromiumos-platform-window_manager,joshfire/chromiumos-platform-window_manager