Revert "Revert "Use float colors for blend constant""

This reverts commit 5a4f2a341a4a32d8f175afe1828a7796155dbcb8.

Bug: skia:
Change-Id: I706009343dc1976311a88d57800a140efd776861
Reviewed-on: https://skia-review.googlesource.com/c/168363
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
11 files changed