SkPDF: handle unsupported colortypes (e.g. F16) uniformly

Change-Id: I1a9e7a749b5be9dc552608493e23a03db9b2c5b1
Reviewed-on: https://skia-review.googlesource.com/25161
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
1 file changed