Remove deprecated field from SkRuntimeEffectBuilder::BuilderChild

Android has been updated to use fChild, so fIndex is dead.

Change-Id: Iec728aa91a4ad47f84e2188ade75f639f0c6087c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/447186
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
1 file changed