Fix bug where coverage on interior of stroked rects is applied twice

When we were not supposed to be folding coverage into alpha we would still
set the innermost rectangle's color to transparent black.

Change-Id: Idfc29da9778f9d7d0381a8084717134e835dc744
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/241882
Commit-Queue: Robert Phillips <robertphillips@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
1 file changed