Do not support index8 for generateScaledPixels

Since the in/out parameter is a const SkPixmap without the proper
color table, there is no way to tell the client about it without
modifying the const SkPixmap. Rather than cheating, just return
false.

Change-Id: I63fdf57febc59e1ee9af13aa6eb9b253d19bcb17
Reviewed-on: https://skia-review.googlesource.com/6414
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
2 files changed