start removing uses of SkScalarMul

BUG=skia:6197

Change-Id: Ic444c7ee4ca547f483dc8232dcacd6d4ba87d913
Reviewed-on: https://skia-review.googlesource.com/8041
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Mike Reed <reed@google.com>
19 files changed