stifle warning in tValue2Scalar()

Spun off from https://skia-review.googlesource.com/c/skia/+/242776.

I was worried there that this indicated a bug, that we're actually
working with a slightly-wrong denominator, but thanks to the wonders of
float rounding, turns out everything's probably ok.  This is the same as
that CL above with unit tests that the important boundary conditions
work correctly.

Change-Id: I1df469daf48df12f0e72778e6af58f5e733452ed
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/242841
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed