Support pngs with incorrect CMF bytes

Bug: chromium:807324

Though these pngs are technically incorrect, many such PNGs exist, and
they are supported in Chromium. Ensure that users of SkCodec (e.g.
Android, Flutter) display them as well.

Change-Id: I2f1e573b4b7039cea81f96397cc0aa4cbc9461c3
Reviewed-on: https://skia-review.googlesource.com/111082
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
1 file changed