--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2605,16 +2605,33 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsSt
 
   // The number of elements in mTransitions that are not from repeating
   // a list due to another property being longer.
   uint32_t mTransitionTimingFunctionCount,
            mTransitionDurationCount,
            mTransitionDelayCount,
            mTransitionPropertyCount;
 
+  nsCSSPropertyID GetTransitionProperty(uint32_t aIndex) const
+  {
+    return mTransitions[aIndex % mTransitionPropertyCount].GetProperty();
+  }
+  float GetTransitionDelay(uint32_t aIndex) const
+  {
+    return mTransitions[aIndex % mTransitionDelayCount].GetDelay();
+  }
+  float GetTransitionDuration(uint32_t aIndex) const
+  {
+    return mTransitions[aIndex % mTransitionDurationCount].GetDuration();
+  }
+  const nsTimingFunction& GetTransitionTimingFunction(uint32_t aIndex) const
+  {
+    return mTransitions[aIndex % mTransitionTimingFunctionCount].GetTimingFunction();
+  }
+
   nsStyleAutoArray<mozilla::StyleAnimation> mAnimations; // [reset]
 
   // The number of elements in mAnimations that are not from repeating
   // a list due to another property being longer.
   uint32_t mAnimationTimingFunctionCount,
            mAnimationDurationCount,
            mAnimationDelayCount,
            mAnimationNameCount,