--- a/dom/base/Element.h
+++ b/dom/base/Element.h
@@ -482,16 +482,26 @@ public:
 
   void UnsetHasDirtyDescendantsForServo() {
     MOZ_ASSERT(IsStyledByServo());
     UnsetFlags(ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
   }
 
   inline void NoteDirtyDescendantsForServo();
 
+  bool HasAnimationOnlyDirtyDescendantsForServo() const {
+    MOZ_ASSERT(IsStyledByServo());
+    return HasFlag(ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
+  }
+
+  void UnsetHasAnimationOnlyDirtyDescendantsForServo() {
+    MOZ_ASSERT(IsStyledByServo());
+    UnsetFlags(ELEMENT_HAS_ANIMATION_ONLY_DIRTY_DESCENDANTS_FOR_SERVO);
+  }
+
 #ifdef DEBUG
   inline bool DirtyDescendantsBitIsPropagatedForServo();
 #endif
 
   bool HasServoData() const {
     return !!mServoData.Get();
   }
 

--- a/layout/base/ServoRestyleManager.cpp
+++ b/layout/base/ServoRestyleManager.cpp
@@ -129,45 +129,48 @@ ServoRestyleManager::PostRebuildAllStyle
   // if we do, we need to re-selector-match them here.
 }
 
 /* static */ void
 ServoRestyleManager::ClearServoDataFromSubtree(Element* aElement)
 {
   if (!aElement->HasServoData()) {
     MOZ_ASSERT(!aElement->HasDirtyDescendantsForServo());
+    MOZ_ASSERT(!aElement->HasAnimationOnlyDirtyDescendantsForServo());
     return;
   }
 
   StyleChildrenIterator it(aElement);
   for (nsIContent* n = it.GetNextChild(); n; n = it.GetNextChild()) {
     if (n->IsElement()) {
       ClearServoDataFromSubtree(n->AsElement());
     }
   }
 
   aElement->ClearServoData();
   aElement->UnsetHasDirtyDescendantsForServo();
+  aElement->UnsetHasAnimationOnlyDirtyDescendantsForServo();
 }
 
-
 /* static */ void
 ServoRestyleManager::ClearRestyleStateFromSubtree(Element* aElement)
 {
-  if (aElement->HasDirtyDescendantsForServo()) {
+  if (aElement->HasDirtyDescendantsForServo() ||
+      aElement->HasAnimationOnlyDirtyDescendantsForServo()) {
     StyleChildrenIterator it(aElement);
     for (nsIContent* n = it.GetNextChild(); n; n = it.GetNextChild()) {
       if (n->IsElement()) {
         ClearRestyleStateFromSubtree(n->AsElement());
       }
     }
   }
 
   Unused << Servo_TakeChangeHint(aElement);
   aElement->UnsetHasDirtyDescendantsForServo();
+  aElement->UnsetHasAnimationOnlyDirtyDescendantsForServo();
   aElement->UnsetFlags(NODE_DESCENDANTS_NEED_FRAMES);
 }
 
 /**
  * This struct takes care of encapsulating some common state that text nodes may
  * need to track during the post-traversal.
  *
  * This is currently used to properly compute change hints when the parent
@@ -439,17 +442,19 @@ ServoRestyleManager::ProcessPostTraversa
     // style or not, we need to call it *after* setting |newContext| to
     // |styleFrame| to ensure the animated transform has been removed first.
     AddLayerChangesForAnimation(styleFrame, aElement, aChangeList);
   }
 
   const bool descendantsNeedFrames =
     aElement->HasFlag(NODE_DESCENDANTS_NEED_FRAMES);
   const bool traverseElementChildren =
-    aElement->HasDirtyDescendantsForServo() || descendantsNeedFrames;
+    aElement->HasDirtyDescendantsForServo() ||
+    aElement->HasAnimationOnlyDirtyDescendantsForServo() ||
+    descendantsNeedFrames;
   const bool traverseTextChildren = recreateContext || descendantsNeedFrames;
   bool recreatedAnyContext = recreateContext;
   if (traverseElementChildren || traverseTextChildren) {
     nsStyleContext* upToDateContext =
       recreateContext ? newContext : oldStyleContext;
 
     StyleChildrenIterator it(aElement);
     TextPostTraversalState textState(
@@ -465,16 +470,17 @@ ServoRestyleManager::ProcessPostTraversa
       } else if (traverseTextChildren && n->IsNodeOfType(nsINode::eTEXT)) {
         recreatedAnyContext |=
           ProcessPostTraversalForText(n, aChangeList, textState);
       }
     }
   }
 
   aElement->UnsetHasDirtyDescendantsForServo();
+  aElement->UnsetHasAnimationOnlyDirtyDescendantsForServo();
   aElement->UnsetFlags(NODE_DESCENDANTS_NEED_FRAMES);
   return recreatedAnyContext;
 }
 
 bool
 ServoRestyleManager::ProcessPostTraversalForText(
     nsIContent* aTextNode,
     nsStyleChangeList& aChangeList,