Clean up Sample3D math a bit, fix a bug with world-space

The localToWorld matrix was still offset, because is was being
tagged while the transform still had things offset from the origin.
I've moved where it's marked to fix that bug, renamed the ID,
and done some other minor cleanup to hopefully clarify how things
fit together.

Change-Id: Idccc419882a2e89dee14128a6096ad7566d57f99
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/285103
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed