In runtime effects, treat all children as sampled

An unused child that used its coordinates would triggers asserts in the
GP - we expect that all FPs are sampled/invoked. This generates slightly
sub-optimal code (we compute and interpolate the local coordinates for
that child FP), but it's not likely to happen in real code.

Bug: skia:12429
Change-Id: Ic2ddc65d16a7e1f47af8c4192e5ff9ea329bf335
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/446836
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
3 files changed