Be able to fuzz a directory of input

BUG=skia:5878

Change-Id: I13552948c86a83f2384b83f59432c11779f305f1
Reviewed-on: https://skia-review.googlesource.com/6528
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed