- we now check for bitwise equality of files before bothering with pixel
comparisons (this will help with formats for which we don't have good
decoders, like PDF)
- unparsable files are now reported as differing, unless they are bitwise equal
(before, they were always reported as matching!)
- "largest area mismatch" is now based on same-size image pairs only;
previously, if any image pairs had mismatching size, it was 100%
- removed repetitive "image size mismatch, so no diff to display" messages
- changed format of leftmost table cells to be more readable
BUG=http://code.google.com/p/skia/issues/detail?id=473
Review URL: https://codereview.appspot.com/6208089
git-svn-id: http://skia.googlecode.com/svn/trunk@4027 2bbb7eff-a529-9590-31e7-b0007b416f81
