Remove invokeChild variants that write to output color

Change-Id: I1788cd621704f580ff0c7d930138d463b724f314
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/266556
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed