Reland "Delete legacy shadeSpan implementation of Perlin Noise."

Chromium was rebaselined at https://crrev.com/c/5323882.

Original change's description:
> Revert "Delete legacy shadeSpan implementation of Perlin Noise."
>
> This reverts commit 8589595721d09bd54ca694f75263846f400096da.
>
> Reason for revert: output visibly different
>
> Original change's description:
> > Delete legacy shadeSpan implementation of Perlin Noise.
> >
> > A CL was set up to rebaseline Chrome at https://crrev.com/c/5323882,
> > but it came up with zero image errors.
> >
> > Bug: b/40045243
> > Change-Id: I9c0ae2920ebaf56dcb931a57317ad2de0553d8f0
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/817622
> > Reviewed-by: Brian Osman <brianosman@google.com>
> > Commit-Queue: John Stiles <johnstiles@google.com>
>
> Bug: b/40045243
> Change-Id: I07e8e6abdadfa64693c18decd075a46fbee0e231
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/819520
> Auto-Submit: John Stiles <johnstiles@google.com>
> Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

Bug: b/40045243
Change-Id: Ie6a29e9395c826d6352676ff7a41aadaff20481f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/819644
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
3 files changed