diff --git a/layout/style/AnimationCommon.h b/layout/style/AnimationCommon.h
index cf7154195ae..235ae20ded2 100644
--- a/layout/style/AnimationCommon.h
+++ b/layout/style/AnimationCommon.h
@@ -474,6 +474,23 @@ struct CommonElementAnimationData : public PRCList
   bool CanPerformOnCompositorThread(CanAnimateFlags aFlags) const;
   bool HasAnimationOfProperty(nsCSSProperty aProperty) const;
 
+  bool IsForElement() const { // rather than for a pseudo-element
+    return mElementProperty == nsGkAtoms::animationsProperty ||
+           mElementProperty == nsGkAtoms::transitionsProperty;
+  }
+
+  nsString PseudoElement()
+  {
+    if (IsForElement()) {
+      return EmptyString();
+    } else if (mElementProperty == nsGkAtoms::animationsOfBeforeProperty ||
+               mElementProperty == nsGkAtoms::transitionsOfBeforeProperty) {
+      return NS_LITERAL_STRING("::before");
+    } else {
+      return NS_LITERAL_STRING("::after");
+    }
+  }
+
   static void LogAsyncAnimationFailure(nsCString& aMessage,
                                        const nsIContent* aContent = nullptr);
 
diff --git a/layout/style/nsAnimationManager.h b/layout/style/nsAnimationManager.h
index 21a8648e139..0bb1abbefd5 100644
--- a/layout/style/nsAnimationManager.h
+++ b/layout/style/nsAnimationManager.h
@@ -62,19 +62,6 @@ struct ElementAnimations MOZ_FINAL
 
   void GetEventsAt(TimeStamp aRefreshTime, EventArray &aEventsToDispatch);
 
-  bool IsForElement() const { // rather than for a pseudo-element
-    return mElementProperty == nsGkAtoms::animationsProperty;
-  }
-
-  nsString PseudoElement()
-  {
-    return mElementProperty == nsGkAtoms::animationsProperty ?
-             EmptyString() :
-             mElementProperty == nsGkAtoms::animationsOfBeforeProperty ?
-               NS_LITERAL_STRING("::before") :
-               NS_LITERAL_STRING("::after");
-  }
-
   void PostRestyleForAnimation(nsPresContext *aPresContext) {
     nsRestyleHint styleHint = IsForElement() ? eRestyle_Self : eRestyle_Subtree;
     aPresContext->PresShell()->RestyleForAnimation(mElement, styleHint);
diff --git a/layout/style/nsTransitionManager.cpp b/layout/style/nsTransitionManager.cpp
index 23fdf38482c..2beb01317ba 100644
--- a/layout/style/nsTransitionManager.cpp
+++ b/layout/style/nsTransitionManager.cpp
@@ -848,11 +848,7 @@ nsTransitionManager::FlushTransitions(FlushFlags aFlags)
           events.AppendElement(
             TransitionEventInfo(et->mElement, prop,
                                 anim->mTiming.mIterationDuration,
-                                ep == nsGkAtoms::transitionsProperty ?
-                                  EmptyString() :
-                                  ep == nsGkAtoms::transitionsOfBeforeProperty ?
-                                    before :
-                                    after));
+                                et->PseudoElement()));
 
           // Leave this transition in the list for one more refresh
           // cycle, since we haven't yet processed its style change, and