[skottie] Ensure static split-position properties are committed

We currently drop static split-position adapters without commiting the
value to the scene graph.

TBR=
Change-Id: Id5852da35345fa58ecaf6c752456ecb32e5b405a
Reviewed-on: https://skia-review.googlesource.com/136782
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

modules/skottie/src/SkottieAnimator.cpp

@@ -298,7 +298,8 @@ public:
         }
 
         if (split_animator->fAnimators.empty()) {
-            // Static split property, no need to hold on to the split animator.
+            // Static split property: commit the (buffered) value and discard.
+            split_animator->onTick(0);
             return nullptr;
         }