* clutter/cogl/gl/cogl-texture.c (_cogl_texture_upload_subregion_to_gl)
(_cogl_texture_upload_to_gl):
* clutter/cogl/gles/cogl-texture.c (_cogl_texture_upload_to_gl)
(_cogl_texture_upload_subregion_to_gl):
When uploading data to a sliced texture, fill the waste pixels
with copies of the edge of the real texture data. Otherwise the
value of the waste pixels are undefined so it will show artifacts
when the texture is scaled with GL_LINEAR and the pixels are
blended in.