In skimage, copy to 8888 if encoding fails.

When writing the bitmap for visual comparison, rather than special
casing A8, depend on the fact that the encoder will fail, and try
copying to 8888 and encoding that if so.

R=reed@google.com

Review URL: https://codereview.chromium.org/25964003

git-svn-id: http://skia.googlecode.com/svn/trunk@11633 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed