1 files changed, 13 insertions, 1 deletions
diff --git a/dom/base/FragmentOrElement.cpp b/dom/base/FragmentOrElement.cpp
index e341ae315..a851190ff 100644
--- a/dom/base/FragmentOrElement.cpp
+++ b/dom/base/FragmentOrElement.cpp
@@ -589,6 +589,13 @@ FragmentOrElement::nsDOMSlots::Traverse(nsCycleCollectionTraversalCallback &cb)
         mExtendedSlots->mCustomElementData->mReactionQueue[i]->Traverse(cb);
       }
     }
+
+    if (mExtendedSlots->mCustomElementData->mCustomElementDefinition) {
+      NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb,
+        "mExtendedSlots->mCustomElementData->mCustomElementDefinition");
+      cb.NoteNativeChild(mExtendedSlots->mCustomElementData->mCustomElementDefinition,
+        NS_CYCLE_COLLECTION_PARTICIPANT(CustomElementDefinition));
+    }
   }
 
   for (auto iter = mExtendedSlots->mRegisteredIntersectionObservers.Iter();
@@ -625,7 +632,12 @@ FragmentOrElement::nsDOMSlots::Unlink()
   mExtendedSlots->mContainingShadow = nullptr;
   MOZ_ASSERT(!(mExtendedSlots->mXBLBinding));
   mExtendedSlots->mXBLInsertionParent = nullptr;
-  mExtendedSlots->mCustomElementData = nullptr;
+  if (mExtendedSlots->mCustomElementData) {
+    if (mExtendedSlots->mCustomElementData->mCustomElementDefinition) {
+      mExtendedSlots->mCustomElementData->mCustomElementDefinition = nullptr;
+    }
+    mExtendedSlots->mCustomElementData = nullptr;
+  }
   mExtendedSlots->mRegisteredIntersectionObservers.Clear();
   nsCOMPtr<nsIFrameLoader> frameLoader =
     do_QueryInterface(mExtendedSlots->mFrameLoaderOrOpener);