--- a/dom/animation/KeyframeEffectReadOnly.cpp
+++ b/dom/animation/KeyframeEffectReadOnly.cpp
@@ -1355,23 +1355,17 @@ KeyframeEffectReadOnly::CanThrottleTrans
   // If we know that the animation cannot cause overflow,
   // we can just disable flushes for this animation.
 
   // If we don't show scrollbars, we don't care about overflow.
   if (LookAndFeel::GetInt(LookAndFeel::eIntID_ShowHideScrollbars) == 0) {
     return true;
   }
 
-  nsPresContext* presContext = GetPresContext();
-  // CanThrottleTransformChanges is only called as part of a refresh driver tick
-  // in which case we expect to has a pres context.
-  MOZ_ASSERT(presContext);
-
-  TimeStamp now =
-    presContext->RefreshDriver()->MostRecentRefresh();
+  TimeStamp now = aFrame.PresContext()->RefreshDriver()->MostRecentRefresh();
 
   EffectSet* effectSet = EffectSet::GetEffectSet(mTarget->mElement,
                                                  mTarget->mPseudoType);
   MOZ_ASSERT(effectSet, "CanThrottleTransformChanges is expected to be called"
                         " on an effect in an effect set");
   MOZ_ASSERT(mAnimation, "CanThrottleTransformChanges is expected to be called"
                          " on an effect with a parent animation");
   TimeStamp lastSyncTime = effectSet->LastTransformSyncTime();