This changed behavior when asLegacyBitmap() was modified to always
initiate a decode in legacy mode.
This fixes the gm to work as originally intended.
BUG=skia:
Change-Id: I34d35f6f445bd4606c6e28f83905702ec0b36bbb
Reviewed-on: https://skia-review.googlesource.com/5696
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>