Caches MipLevel in TextureStorage11, to avoid repeated GetDesc calls. TRAC #22341 Author: Shannon Woods Signed-off-by: Nicolas Capens Signed-off-by: Daniel Koch git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1693 736b8ea6-26fd-11df-bfd4-992fa37f6226