Fix typo that caused shadings using functions to clobber the destination colors.
Fix typo that caused shadings using functions to clobber the destination colors.

Ignore-this: 49d82166d2463acba1002b132b497d05

darcs-hash:20100701151856-f546f-d398e1b6552cfd0786db058dcac82360628a36d2.gz

nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf,nqv/mupdf