SkSplicer: favor 1.0f as a constant.

SkSplicer: favor 1.0f as a constant.

1.0f is the most commonly used constant, so we put it first in the
constant struct.  This usually cuts an instruction off loading it.

Change-Id: Ie54a9482aa3e90e9e5d8fcaa40dbd353af0fa1ca
Reviewed-on: https://skia-review.googlesource.com/7367
Reviewed-by: Mike Klein <mtklein@chromium.org>