Add tonal color support for shadows.

Bug: skia:
Change-Id: Ib9bd9083da1d8a9fa90ae7c710386e6903541fd5
Reviewed-on: https://skia-review.googlesource.com/18148
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
7 files changed