--- a/layout/style/nsAnimationManager.cpp
+++ b/layout/style/nsAnimationManager.cpp
@@ -407,23 +407,17 @@ nsAnimationManager::UpdateAnimations(nsS
 
   if (newAnimations.IsEmpty()) {
     if (collection) {
       collection->Destroy();
     }
     return;
   }
 
-  if (collection) {
-    EffectSet* effectSet =
-      EffectSet::GetEffectSet(aElement, aStyleContext->GetPseudoType());
-    if (effectSet) {
-      effectSet->UpdateAnimationGeneration(mPresContext);
-    }
-  } else {
+  if (!collection) {
     bool createdCollection = false;
     collection =
       CSSAnimationCollection::GetOrCreateAnimationCollection(
         aElement, aStyleContext->GetPseudoType(), &createdCollection);
     if (!collection) {
       MOZ_ASSERT(!createdCollection, "outparam should agree with return value");
       NS_WARNING("allocating collection failed");
       return;