--- a/layout/style/nsAnimationManager.cpp
+++ b/layout/style/nsAnimationManager.cpp
@@ -464,16 +464,19 @@ protected:
     mCollection->mAnimations.SwapElements(mNewAnimations);
 
     // Cancel removed animations
     for (size_t newAnimIdx = mNewAnimations.Length(); newAnimIdx-- != 0; ) {
       mNewAnimations[newAnimIdx]->CancelFromStyle();
     }
   }
 
+  virtual void SetKeyframes(KeyframeEffectReadOnly& aEffect,
+                            nsTArray<Keyframe>&& aKeyframes) = 0;
+
   nsAnimationManager* mManager;
   RefPtr<dom::Element> mTarget;
   CSSPseudoElementType mPseudoType;
   RefPtr<dom::DocumentTimeline> mTimeline;
   // Existing collection, nullptr if the target element has no animations.
   nsAnimationManager::CSSAnimationCollection* mCollection;
   OwningCSSAnimationPtrArray mNewAnimations;
 };
@@ -490,16 +493,23 @@ public:
     nsAnimationManager::CSSAnimationCollection* aCollection)
     : CSSAnimationBuilder(aAnimationManager, aTarget, aPseudoType, aCollection)
     , mComputedValues(aComputedValues)
     , mParentComputedValues(aParentComputedValues)
   {
     MOZ_ASSERT(aComputedValues);
   }
 
+protected:
+  void SetKeyframes(KeyframeEffectReadOnly& aEffect,
+                    nsTArray<Keyframe>&& aKeyframes) override
+  {
+    aEffect.SetKeyframes(Move(aKeyframes),
+                         { mComputedValues, mParentComputedValues });
+  }
 private:
   const ServoComputedValues* mComputedValues;
   const ServoComputedValues* mParentComputedValues;
 };
 
 class MOZ_STACK_CLASS GeckoCSSAnimationBuilder final
   : public CSSAnimationBuilder {
 public:
@@ -512,16 +522,24 @@ public:
     : CSSAnimationBuilder(aAnimationManager, aTarget, aPseudoType, aCollection)
     , mStyleContext(aStyleContext)
   {
     MOZ_ASSERT(aStyleContext);
   }
 
   void BuildAnimations();
 
+
+protected:
+  void SetKeyframes(KeyframeEffectReadOnly& aEffect,
+                    nsTArray<Keyframe>&& aKeyframes) override
+  {
+    aEffect.SetKeyframes(Move(aKeyframes), mStyleContext);
+  }
+
 private:
   // Returns a new animation set up with given StyleAnimation.
   // Or returns an existing animation matching StyleAnimation's name updated
   // with the new StyleAnimation.
   already_AddRefed<CSSAnimation> Build(const StyleAnimation& aSrc);
 
   void
   UpdateOldAnimationPropertiesWithNew(CSSAnimation& aOld,
@@ -577,17 +595,17 @@ GeckoCSSAnimationBuilder::UpdateOldAnima
   // identity (and any expando properties attached to it).
   if (aOld.GetEffect()) {
     dom::AnimationEffectReadOnly* oldEffect = aOld.GetEffect();
     animationChanged = oldEffect->SpecifiedTiming() != aNewTiming;
     oldEffect->SetSpecifiedTiming(aNewTiming);
 
     KeyframeEffectReadOnly* oldKeyframeEffect = oldEffect->AsKeyframeEffect();
     if (oldKeyframeEffect) {
-      oldKeyframeEffect->SetKeyframes(Move(aNewKeyframes), mStyleContext);
+      SetKeyframes(*oldKeyframeEffect, Move(aNewKeyframes));
     }
   }
 
   // Handle changes in play state. If the animation is idle, however,
   // changes to animation-play-state should *not* restart it.
   if (aOld.PlayState() != AnimationPlayState::Idle) {
     // CSSAnimation takes care of override behavior so that,
     // for example, if the author has called pause(), that will
@@ -670,17 +688,17 @@ GeckoCSSAnimationBuilder::Build(const St
   Maybe<OwningAnimationTarget> target;
   target.emplace(mTarget, mPseudoType);
   KeyframeEffectParams effectOptions;
   RefPtr<KeyframeEffectReadOnly> effect =
     new KeyframeEffectReadOnly(mManager->PresContext()->Document(),
                                target, timing,
                                effectOptions);
 
-  effect->SetKeyframes(Move(keyframes), mStyleContext);
+  SetKeyframes(*effect, Move(keyframes));
 
   RefPtr<CSSAnimation> animation =
     new CSSAnimation(mManager->PresContext()->Document()->GetScopeObject(),
                      aSrc.GetName());
   animation->SetOwningElement(
     OwningElementRef(*mTarget, mPseudoType));
 
   animation->SetTimelineNoUpdate(mTimeline);