Adds a utility function to calculate the size of a pixel given a DXGI format. TRAC #22208 Author: Shannon Woods Signed-off-by: Geoff Lang Signed-off-by: Daniel Koch git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1590 736b8ea6-26fd-11df-bfd4-992fa37f6226