Fix LayoutAnimations assertion on `adjustDelayedMutationIndicesForMutation`

Summary:
`adjustDelayedMutationIndicesForMutation` asserts that the mutation is either Remove or Insert. At one callsite, we weren't checking the mutation type before calling `adjustDelayedMutationIndicesForMutation`.

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D23746617

fbshipit-source-id: 6046fec2eb4821094937b1b16f40347bbc55c20e

ReactCommon/react/renderer/animations/LayoutAnimationKeyFrameManager.cpp

@@ -1253,7 +1253,10 @@ LayoutAnimationKeyFrameManager::pullTransaction(
           << "Adjust delayed mutations based on finalConflictingMutations";
 #endif
       for (auto &mutation : finalConflictingMutations) {
-        adjustDelayedMutationIndicesForMutation(surfaceId, mutation);
+        if (mutation.type == ShadowViewMutation::Remove ||
+            mutation.type == ShadowViewMutation::Insert) {
+          adjustDelayedMutationIndicesForMutation(surfaceId, mutation);
+        }
       }
 
       // Adjust keyframes based on already-delayed, existing animations, before